This guide will help you understand how to properly cite sources in ACS format, the standard citation style for chemistry and biochemistry research, ensuring that your academic work meets the American Chemical Society's guidelines outlined in the ACS Guide to Scholarly Communication.
Jan 3, 2026
By
Joe Pacal, MSc
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TL;DR
ACS style offers three in-text options: superscript numbers¹, italic parenthetical numbers (1), or author-date (Smith, 2023). Pick one and stay consistent. This guide covers reference formats for journals, books, and patents, plus CASSI journal abbreviations. DOIs are required when available. Perfect for chemistry, biochemistry, and chemical engineering research.
The Official Source
The ACS Guide to Scholarly Communication (2020) is the current official resource, published online by the American Chemical Society. It supersedes the print ACS Style Guide, 3rd Edition (2006) by Anne M. Coghill and Lorrin R. Garson.
Access the guide at pubs.acs.org/doi/book/10.1021/acsguide.
Quick Overview
ACS uses a numbered citation system with three format options for in-text citations:
Superscript numbers — Most common
Italic numbers in parentheses — Alternative format
Author name with number — When emphasizing the author
References are numbered in the order they first appear in the text.
In-Text Citations
Choose one format and use it consistently throughout your paper.
Superscript Numbers (Most Common)
The reaction mechanism has been well documented.¹
Parker⁴ demonstrated that minimal condensation is expected.
Italic Numbers in Parentheses
The reaction mechanism has been well documented (1).
Chen (9) attributes the slowdown to measurement errors.
Multiple Citations
Several studies support this conclusion.¹⁻³,⁷
Reference List Basics
The reference list is titled "References" and numbered consecutively in citation order.
Basic Structure
#. Author 1; Author 2; Author 3. Title of Article. Journal Abbreviation Year, Volume, Pages. DOI.
Journal Article
Reinke, A. A.; Gestwicki, J. E. Insight into Amyloid Structure Using Chemical Probes. Chem. Biol. Drug Des. 2011, 77, 399–411.
Journal Article with DOI
Lu, H.; Tournet, J.; Dastafkan, K. Noble Metal-Free Electrocatalytic Hydrogen Oxidation. Angew. Chem. Int. Ed. 2021, 60, 14865–14871. DOI: 10.1002/anie.202014679.
Book
Carey, F. A.; Sundberg, R. J. Advanced Organic Chemistry, 5th ed.; Springer: New York, 2007.
Chapter in Book
Asmus, K. D. Recent Aspects of Thiyl and Perthiyl Free Radical Chemistry. In Active Oxygens, Lipid Peroxides, and Antioxidants; Yagi, K., Ed.; Japan Scientific Societies: Tokyo, 1993; pp 57–67.
Website
National Institute of Standards and Technology. NIST Chemistry WebBook. https://webbook.nist.gov/chemistry/ (accessed 2024-01-15).
Patent
Heller, A. Biological Fuel Cell and Methods. U.S. Patent 9,070,934, June 30, 2015.
Key ACS Conventions
Journal abbreviations — Always abbreviate journal names using Chemical Abstracts Service Source Index (CASSI) standards. Search at cassi.cas.org.
Author format — Last name, initials (no periods): Smith, A. B.
Semicolons between authors — Unlike most styles, ACS uses semicolons: Smith, A. B.; Jones, C. D.
Bold year — The publication year is bolded in the reference.
Italic volume — Journal volume numbers are italicized.
No issue numbers — ACS typically omits issue numbers for journals.
DOI format — Include when available: DOI: 10.xxxx/xxxxx
Publisher location — For large publishers (ACS, Wiley, Elsevier, Springer), location is optional.
Common Mistakes to Avoid
Wrong journal abbreviations — Always verify abbreviations in CASSI. "Journal of the American Chemical Society" becomes J. Am. Chem. Soc.
Periods in author initials — Use Smith, A. B. not Smith, A.B. or Smith, A. B..
Commas between authors — Use semicolons, not commas: Smith, A. B.; Jones, C. D.
Missing bold/italics — Year should be bold; volume should be italic.
Alphabetizing references — ACS references are numbered by citation order, not alphabetically.
Including issue numbers — ACS style typically omits issue numbers for journal articles.
Who Uses ACS Style?
ACS is the standard for:
Chemistry journals (especially ACS publications)
Chemical engineering
Biochemistry and molecular biology
Materials science
Pharmaceutical sciences
Environmental chemistry
If you're submitting to an ACS journal or studying chemistry, this is your citation style.
ACS vs. Other Science Styles
Element | ACS | APA | IEEE |
|---|---|---|---|
In-text format | Superscript or (italic) | (Author, Year) | [#] |
Author separator | Semicolon | Comma/& | Semicolon |
Year format | Bold | Not bold | Not bold |
Journal abbreviation | Required (CASSI) | Optional | Required (IEEE) |
Further Resources
ACS Guide to Scholarly Communication — Official online resource
CASSI Search — Journal abbreviation lookup
ACS Author Guidelines — Submission requirements
Need help generating ACS citations? Research tools like Wonders can export your sources in ACS format automatically.
