Guidelines for Reviewers

Peer review is an essential part of the publication process, and it ensures that MDPI maintains the highest standards for its papers. All manuscripts submitted to our journals are strictly and thoroughly peer-reviewed by experts.

Immediately after submission, the journal’s Managing Editor performs a technical pre-check of the manuscript. A suitable Academic Editor is notified of the submission and invited to perform an editorial pre-check and recommend reviewers. The Academic Editor can decide to continue with the peer review process, reject the manuscript, or request revision before peer review. If continuing the peer review process, the Editorial Office organizes the peer review, who are independent experts, and collects at least two review reports per manuscript. We ask authors to make sufficient revision (with a second round of peer review when necessary) before a final decision is made. The final decision is made by an Academic Editor (usually the Editor-in-Chief/Editorial Board Member of a journal or the Guest Editor of a Special Issue). Accepted manuscripts then undergo internal copy-editing and English editing. More details about the editorial process can be found here. A brochure for reviewers can be found here.

The role of the reviewer is vital, and they bear a great responsibility in ensuring the integrity of the scholarly record. Every reviewer is expected to evaluate manuscripts in a timely, transparent, and ethical manner, following the COPE guidelines  https://publicationethics.org/files/cope-ethical-guidelines-peer-reviewers-v2_0.pdf.

Reviewers should meet the following criteria:

• They should have no conflicts of interest with any of the authors;
• They should not be part of the same institution as the authors;
• They should not have published with the authors in the past three years;
• They should hold a PhD or MD (applicable for medical journals);
• They should have relevant experience and a proven publication record in the field of the submitted paper (accessible through Scopus or ORCID);
• They should be experienced scholars in the field of the submitted paper;
• They should hold an official and recognized academic affiliation.

MDPI requires rigorous peer review to ensure the thorough evaluation of each manuscript; this is a fundamental task for our reviewers. Reviewers are expected to meet the following requirements:

• They must have the necessary expertise to judge the scientific quality of manuscripts;
• They need to provide high-quality review reports and remain responsive throughout the peer review process;
• They must maintain standards of professionalism and ethics.

Reviewing is a crucial yet often unseen and unrewarded task. We are committed to recognizing the efforts of all our reviewers.

Reviewing for MDPI journals includes the following benefits:

• For every manuscript reviewed, the reviewer may receive a discount voucher code entitling them to a reduction in the article processing charge (APC) of a future submission to any MDPI journal. This voucher is linked to the reviewer’s email address and can be applied online during submission or at any time before the manuscript is accepted. Note that vouchers cannot be used after an invoice has been issued upon the acceptance of a manuscript. If an article is rejected, the voucher can instead be used for a future submission. Please note that reviewer vouchers can only be combined with IOAP and affiliated society discounts.

• Reviewer voucher codes can be used to pay for professional English editing through Author Services professional English editing.

• Reviewers receive a personalized reviewer certificate.

• Reviewers are eligible to be considered for the Outstanding Reviewer Awards.

• Reviewers are included in a journal’s annual acknowledgment of reviewers if more than 50 reviewers assisted the journal in the previous year.

• Excellent reviewers may be promoted to Reviewer Board Members (subject to approval by the Editor-in-Chief).

• Reviewers may create a profile on the Web of Science Reviewer Recognition Service (formerly Publons) and have their reviewing activity automatically added for participating journals; these profiles can also be integrated with ORCID.

The Reviewer Board (RB) consists of experienced researchers whose main responsibility is to regularly and actively support journals by providing high-quality, rigorous, and transparent review reports for submitted manuscripts within their area of expertise. The initial term is 1 year and can then be renewed or terminated. Membership involves the same responsibilities and benefits as those for regular reviewers, with the addition of the following:

1. RB Members must review a minimum of six manuscripts per year. Should the reviewer be unable to provide a report when invited, they are expected to suggest alternative potential reviewers (the proposed candidates must meet the reviewers’ requirements from Section 2).

2. RB Members are entitled to receive an RB certificate.

3. RB Members are announced on the journal website.

MDPI journals are actively looking for volunteers to review manuscripts. MDPI’s Reviewer Board Members and Volunteer Reviewers can offer to review articles in one or more of MDPI’s journals.

To become part of this program, you must fulfil the criteria outlined in Section 2 entitled “Reviewers’ Profile and Responsibilities”.

To become a member of this program, please apply here. The Editorial Office of the selected journal will be notified and your application will be reviewed by our internal staff, who will verify that your background suits the scope of the journal and address any potential ethical issues. Should you pass our internal check, your application will be approved.

Active Volunteer Reviewers may be promoted to Reviewer Board Members (subject to approval by the Editor-in-Chief).

To apply to review a manuscript as a Reviewer Board Member or Volunteer Reviewer, you can visit the “Recruiting Reviewers” menu in our Submission System (SuSy) (https://susy.mdpi.com/reviewer/list/recruiting_reviewers_manuscripts), which is visible on the left-hand side under “Reviewers Menu”. Here, you can see all the manuscripts that you can apply for*. You can search by journals and keywords. Should you find a manuscript that you would like to review, please click on “Apply”. The Editorial Office of the respective journal will be notified about your application, and our internal staff will inspect your research background and address any potential conflicts of interest. Should you pass, your application to review will be approved.

• Please note that you can only see and apply to manuscripts in journals for which you are a Reviewer Board Member or Volunteer Reviewer.

7.1. Invitation to Review

Manuscripts submitted to MDPI journals are reviewed by at least two experts, who can be Volunteer Reviewers, Reviewer Board Members, or reviewers suggested by the Academic Editor during the preliminary check. The reviewers are asked to evaluate the quality of the manuscript and provide a recommendation to the external editor on whether the manuscript should be accepted, requires revision, or should be rejected.

We ask invited reviewers to do the following:

• Accept or decline any invitations at their earliest convenience (based on the manuscript’s title and abstract);

• Suggest alternative reviewers if an invitation must be declined;

• Promptly request a deadline extension if more time is required to provide a comprehensive report.

7.2. Potential Conflicts of Interest

We ask reviewers to declare any potential conflicts of interest and email the journal’s Editorial Office if they are unsure if something constitutes a potential conflict of interest. Possible conflicts of interest include (but are not limited to) the following:

• The reviewer works at the same institute as one of the authors;

• The reviewer has been a co-author, collaborator, or joint grant holder or has had any other academic link with any of the authors within the past three years;

• The reviewer has a close personal relationship with, rivalry with, or antipathy to any of the authors;

• The reviewer may financially gain or lose from the publication of the paper in any way;

• The reviewer has any other non-financial conflicts of interest (political, personal, religious, ideological, academic, intellectual, or commercial, among others) with any of the authors.

Reviewers should disclose any conflicts of interest that may be perceived as bias for or against the paper or authors.

Please kindly note that if reviewers are asked to assess a manuscript they previously reviewed for another journal, as this is not considered a conflict of interest. In this case, reviewers should feel free to let the Editorial Office know if the manuscript has been improved or not compared to the previous version.

Reviewers are also advised to read the relevant descriptions in the Ethical Guidelines For Peer Reviewers by the Committee on Publication Ethics (COPE).

7.3. Declaration of Confidentiality

MDPI journals operate single- or double-blind peer review (https://www.mdpi.com/editorial_process). Until an article is published, the reviewers should keep the content of the manuscript, including the abstract, confidential. The reviewers should also be careful to not reveal their identity to the authors, either in their comments or in metadata for reports submitted in Microsoft Word or PDF format. Reviewers must inform the Editorial Office if they would like a colleague to complete the review on their behalf (reviewers should always meet the criteria reported in Section 2).

MDPI journals offer the opportunity for authors to publish review reports together with their paper (open peer review) and for reviewers to sign their open peer review reports once “Open Peer Review” (https://www.mdpi.com/editorial_process) has been selected by the authors. However, this will only be carried out upon publication with the reviewers’ permission. In all other cases, review reports are considered confidential and will only be disclosed with the explicit permission of the reviewers.

7.4. Review Reports

Review reports must be written in English. We list some general instructions regarding review reports below.

To begin with, please consider the following guidelines:

• Reviewers should read the whole article as well as the Supplementary Materials, if applicable, paying close attention to the figures, tables, data, and methods.

• Your report should critically analyze the article as a whole but also specific sections and the key concepts presented in the article.

• Reviewers should critically analyze the article as a whole, in addition to specific sections and the key concepts presented.

• Comments should be detailed so that the authors may correctly understand and address the points raised.

• Reviewers must not recommend excessive citations of their work (self-citations), another author’s work (honorary citations), or articles from the journal to which the manuscript was submitted as a means of increasing the number of citations of the reviewer/author/journal. References can be provided as needed, but they must clearly improve the quality of the manuscript under review.

• Reviewers should maintain a neutral tone and focus on providing constructive criticism that will help the authors improve their manuscript. Derogatory comments will not be tolerated.

• GenAI tools and other large language models (LLMs) should not be used by reviewers in the preparation of review reports. Reviewers are solely responsible for the content of their reports, and the utilization of these tools may violate confidentiality, proprietary, and data privacy rights. Limited use to improve the written quality of a peer-review report, such as correcting grammar, structure, spelling, punctuation and formatting, may be acceptable but should be disclosed upon the submission of the peer-review report. Under no circumstances should reviewers upload manuscripts, either in whole or in part, images, figures, tables or any kind of communication related to unpublished manuscripts to any GenAI tools, as to do so violates MDPI’s confidentiality policy relating to peer-review. If it is determined that AI tools have been inappropriately used in the preparation of a review report, the report will be discarded.

Note that MDPI journals follow several standards and guidelines, including those from the ICMJE (medical journals), CONSORT (reporting trials), TOP (data transparency and openness), PRISMA (systematic reviews and meta-analyses), and ARRIVE (reporting in vivo experiments). See the Publishing Standards and Guidelines page or contact an Editorial Office for more details. Reviewers that are familiar with these guidelines should report any concerns they have about their implementation.

For further guidance on writing a critical review, please refer to the following documents:

1. COPE Ethical Guidelines for Peer Reviewers. Committee on Publication Ethics. Available online.

2. Hames, I. Peer Review and Manuscript Management in Scientific Journals: Guidelines for Good Practice. Wiley-Blackwell: Oxford, UK, 2007.

3. Writing a journal article review. Australian National University: Canberra, Australia, 2010. Available online.

4. Golash-Boza, T. How to write a peer review for an academic journal: Six steps from start to finish. Available online.

Review reports should contain the following:

• A brief summary (one short paragraph) outlining the aim of the paper, its main contributions and strengths.

• General concept comments

  • Article: highlighting areas of weakness, the testability of the hypothesis, methodological inaccuracies, missing controls, etc.
  • Review: commenting on the completeness of the review topic covered, the relevance of the review topic, the gap in knowledge identified, the appropriateness of references, etc. These comments are focused on the scientific content of the manuscript and should be specific enough for the authors to be able to respond.

• Specific comments referring to line numbers, tables or figures that point out inaccuracies within the text or sentences that are unclear. These comments should also focus on the scientific content and not on spelling, formatting or English language problems, as these can be addressed at a later stage by our internal staff.

General questions to help guide your review report for research articles:


• Is the manuscript clear, relevant for the field and presented in a well-structured manner?

• Are the cited references mostly recent publications (within the last 5 years) and relevant? Does it include an excessive number of self-citations?

• Is the manuscript scientifically sound and is the experimental design appropriate to test the hypothesis?

• Are the manuscript’s results reproducible based on the details given in the methods section?

• Are the figures/tables/images/schemes appropriate? Do they properly show the data? Are they easy to interpret and understand? Is the data interpreted appropriately and consistently throughout the manuscript? Please include details regarding the statistical analysis or data acquired from specific databases.

• Are the conclusions consistent with the evidence and arguments presented?

• Please evaluate the ethics statements and data availability statements to ensure they are adequate.

General questions to help guide your review report for review articles:


• Is the review clear, comprehensive and of relevance to the field? Is a gap in knowledge identified?

• Was a similar review published recently and, if yes, is this current review still relevant and of interest to the scientific community?

• Are the cited references mostly recent publications (within the last 5 years) and relevant? Are any relevant citations omitted? Does it include an excessive number of self-citations?

• Are the statements and conclusions drawn coherent and supported by the listed citations?

• Are the figures/tables/images/schemes appropriate? Do they properly show the data? Are they easy to interpret and understand?

The content of your review report will be rated by an Academic Editor from a scientific point of view as well as general usefulness to the improvement of the manuscript. The overall grading results will be used as a reference for potential promotion of Reviewer Board Members, Volunteer Reviewers and regular Reviewers.

7.5. Rating the Manuscript

During the manuscript evaluation, please rate the following aspects:

• Novelty: Is the question original and well-defined? Do the results provide an advancement of the current knowledge?

• Scope: Does the work fit the journal scope*?

• Significance: Are the results interpreted appropriately? Are they significant? Are all conclusions justified and supported by the results? Are hypotheses carefully identified as such?

• Quality: Is the article written in an appropriate way? Are the data and analyses presented appropriately? Are the highest standards for presentation of the results used?

• Scientific Soundness: Is the study correctly designed and technically sound? Are the analyses performed with the highest technical standards? Is the data robust enough to draw conclusions? Are the methods, tools, software, and reagents described with sufficient details to allow another researcher to reproduce the results? Is the raw data available and correct (where applicable)?

• Interest to the Readers: Are the conclusions interesting for the readership of the journal? Will the paper attract a wide readership, or be of interest only to a limited number of people? (Please see the Aims and Scope of the journal.)

• Overall Merit: Is there an overall benefit to publishing this work? Does the work advance the current knowledge? Do the authors address an important long-standing question with smart experiments? Do the authors present a negative result of a valid scientific hypothesis?

• English Level: Is the English language appropriate and understandable?

*At this stage reviewers can also suggest that a manuscript may be more appropriate for publication in another MDPI journal. To save the time and effort of reviewers, authors have the possibility to request the transfer of review reports to another MDPI journal. The full list of journals published by MDPI can be found here.

Manuscripts submitted to MDPI journals should meet the highest standards of publication ethics:

• Manuscripts should only report results that have not been submitted or published before, even in part.

• Manuscripts must be original and should not reuse text from another source without appropriate citation.

• The studies reported should have been carried out in accordance with generally accepted ethical research standards.

If the reviewer becomes aware of any scientific misconduct or fraud, plagiarism or any other unethical behavior related to the manuscript, they should raise these concerns with the in-house editor immediately.

7.6. Overall Recommendation

Please provide an overall recommendation for the next processing stage of the manuscript as follows:

• Accept in Present Form: The paper can be accepted without any further changes.

• Accept after Minor Revisions: The paper can in principle be accepted after revision based on the reviewer’s comments. Authors are given five days for minor revisions.

• Reconsider after Major Revisions: The acceptance of the manuscript would depend on the revisions. The author needs to provide a point-by-point response or provide a rebuttal if some of the reviewer’s comments cannot be revised. A maximum of two rounds of major revision per manuscript is normally provided. Authors will be asked to resubmit the revised paper within ten days and the revised version will be returned to the reviewer for further comments.

• Reject: The article has serious flaws, makes no original contribution, and the paper may be rejected with no offer of resubmission to the journal.

Note that your recommendation is visible only to journal editors, not to the authors. Decisions on revisions, acceptance, or rejections must always be well justified.

7.7. Guidelines for Reviewers for Registered Reports Papers

The review process for Registered Reports is divided into two stages. In Stage 1, reviewers assess study proposals before data is collected. In Stage 2, reviewers consider the full study, including results and interpretation.


When reviewing Stage 1 papers, note that no experimental data or results will be included. Reviewers only need to assess the method, including, for example:

1. The importance and soundness of the proposed hypotheses;

2. The suitability and feasibility of the experimental and analysis methodology;

3. Whether there are sufficient details given to replicate the proposed experimental procedures and analysis;

4. Whether there are sufficient outcome-neutral tests of the hypotheses, including positive controls and quality checks.

Manuscripts that pass Stage 1 peer review may be published immediately or after the successful completion of Stage 2 (at the authors’ discretion). Editorial decisions will not be based on the importance or novelty of the results.

For Stage 2 manuscripts, reviewers will be asked to appraise:

1. Whether the data was adequate to test the proposed hypotheses by satisfying the approved outcome-neutral conditions (such as quality checks, positive controls);


2. Whether the stated hypotheses tested was the same as the approved Stage 1 submission;

3. Whether the authors adhered precisely to the registered experimental procedures or were able to sufficiently justify any changes;

4. Whether any new analyses (not mentioned at Stage 1) are methodologically sound and relevant;

5. Whether the authors’ conclusions are justified given the data.

7.8. Guidelines for Reviewers for Depositing Review Activities into ORCID

MDPI allows reviewers to deposit their review activities into an ORCID iD if the reviewer’s ORCID account is connected to their MDPI Submission System (SuSy) account. To do this, reviewers should register a SuSy account and connect their ORCID here. Once the accounts are connected, reviewers can deposit their review records manually here. These records should then show on the reviewer’s ORCID profile.