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This guide covers how to cite sources in ACS format, the citation style used across chemistry and biochemistry.
The Official Source and What This Page Rests On
The ACS Guide to Scholarly Communication is the current official resource, published online by the American Chemical Society under DOI 10.1021/acsguide. It supersedes the print ACS Style Guide, 3rd Edition (2006), published jointly by the American Chemical Society and Oxford University Press.
The online guide is behind a paywall and pubs.acs.org returns HTTP 403 to automated requests, so this page does not quote it. The rules below follow USC Libraries' ACS citation guide, which reproduces ACS's in-text options and reference templates and names The ACS Guide to Scholarly Communication as its source.
Every worked example below is a real, published source, checked today against Crossref, Open Library, NIST or Google Patents.
Quick Overview
USC's guide sets out three in-text methods, and ACS expects you to pick one and keep to it:
- Superscript numbers — most common in chemistry journals
- Italic numbers in parentheses — alternative format
- Author and date in parentheses — where the author matters to the sentence
References are numbered in the order they first appear in the text.
In-Text Citations
Superscript Numbers
The amyloid structure has been probed with small-molecule reporters.¹
Reinke and Gestwicki¹ set out the case for chemical probes.
Italic Numbers in Parentheses
USC's guide illustrates this form with the sentence "The synthesis of the compound has ben described previously (1)" — the typo is theirs, reproduced here rather than silently repaired. The italic number in parentheses is the part to copy.
The synthesis of the compound has been described previously (1).
Multiple Citations
Several studies support this conclusion.¹⁻³,⁷
Reference List Basics
The list is headed "References" and numbered consecutively in citation order.
Basic Structure
USC's guide gives the journal template as: "Author 1; Author 2; Author 3; etc. Title of Article. Journal Abbreviation Year, Volume, Inclusive Pagination."
#. Author 1; Author 2; Author 3. Title of Article. Journal Abbreviation Year, Volume, Pages.
USC's template stops there, and its separate online-article template ends with "URL (accessed Month Day, Year)" rather than a DOI. ACS's own journals append the DOI instead, in the form DOI: 10.1021/…, which is what the entries below do; that element comes from the ACS records for those articles, not from USC's guide.
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
Eight authors, so the semicolon separator gets a workout:
Lu, H.; Tournet, J.; Dastafkan, K.; Liu, Y.; Ng, Y. H.; Karuturi, S. K.; Zhao, C.; Yin, Z. Noble-Metal-Free Multicomponent Nanointegration for Sustainable Energy Conversion. Chem. Rev. 2021, 121, 10271–10366. DOI: 10.1021/acs.chemrev.0c01328.
Book
Carey, F. A.; Sundberg, R. J. Advanced Organic Chemistry, Part A: Structure and Mechanisms, 5th ed.; Springer: New York, 2007.
Chapter in Book
Çelik, M.; Silah, H.; Uslu, B. Electrochemical Sensors for Water Analysis. In Agricultural Electrochemistry; Manjunatha, J. G., Ed.; ACS Symposium Series; American Chemical Society, 2025; pp 73–105. DOI: 10.1021/bk-2025-1496.ch004.
Website
National Institute of Standards and Technology. NIST Chemistry WebBook, SRD 69. https://webbook.nist.gov/chemistry/ (accessed 2026-09-22).
Patent
Heller, A. Biological Fuel Cell and Methods. U.S. Patent 9,070,934, June 30, 2015.
Key ACS Conventions
- Journal abbreviations — abbreviate journal names using Chemical Abstracts Service Source Index (CASSI) standards. Search free at cassi.cas.org.
- Author format — surname, then initials with periods and a space between them: Reinke, A. A.
- Semicolons between authors — unlike most styles, ACS separates authors with semicolons: Reinke, A. A.; Gestwicki, J. E.
- Bold year, italic volume — the year is bold and the volume italic in the journal template USC reproduces.
- Issue numbers — that template carries year, volume and pages but no issue number.
- DOI at the end — include it whenever the source has one. This element is not in USC's templates; it is the form ACS's own records use.
Common Mistakes to Avoid
- Wrong journal abbreviations — verify in CASSI. "Journal of the American Chemical Society" becomes J. Am. Chem. Soc.
- Commas between authors — use semicolons: Reinke, A. A.; Gestwicki, J. E.
- Missing bold and italics — the year is bold; the volume is italic.
- Alphabetizing references — ACS numbers references by citation order, not alphabetically.
- Mixing in-text systems — pick superscripts, italic parenthetical numbers, or author-date, and keep to it.
Who Uses ACS Style?
ACS is the standard for:
- Chemistry journals, especially ACS's own
- Chemical engineering
- Biochemistry and molecular biology
- Materials science
- Pharmaceutical and environmental chemistry
ACS vs. Other Science Styles
| Element | ACS | APA | IEEE |
|---|---|---|---|
| In-text format | Superscript or (italic number) | (Author, Year) | [#] |
| Author separator | Semicolon | Comma/& | Comma |
| Year format | Bold | Not bold | Not bold |
| Journal abbreviation | Required (CASSI) | Not used | Required (IEEE list) |
Sources for This Page
- USC Libraries. "Citation Styles: American Chemical Society (ACS)." https://libguides.usc.edu/c.php?g=974981&p=7048532 — the three in-text options and the reference templates quoted above.
- The ACS Guide to Scholarly Communication, DOI 10.1021/acsguide (Crossref record; the guide itself is paywalled).
- CAS Source Index (CASSI). https://cassi.cas.org
- Crossref records for the Reinke–Gestwicki and Lu et al. articles and the Çelik et al. chapter; Open Library for Carey–Sundberg (5th ed., 2007); NIST Chemistry WebBook for aspirin, CAS RN 50-78-2; Google Patents for U.S. Patent 9,070,934.
