ACS Citation Format: Rules and Examples
ACS style comes from the American Chemical Society and is used in chemistry and related sciences. Its current guidance is the ACS Guide to Scholarly Communication, which replaced the ACS Style Guide.
Updated 21 October 2026 · EssayWriting.com editorial team
- The current ACS standard is the ACS Guide to Scholarly Communication, which replaced the ACS Style Guide (3rd edition).
- In-text, use superscript numbers, italic numbers in parentheses, or author-date, and keep to one system.
- Separate authors with semicolons and write surname first: Lee, J.; Patel, R.; Chen, Y.
ACS at a glance
| Feature | ACS rule |
|---|---|
| Used in | Chemistry, biochemistry, chemical engineering |
| In-text options | Superscript numbers, italic numbers in parentheses, or author-date (Author, Year) |
| Consistency | Pick one in-text method and use it throughout |
| Author names | Surname, initials, separated by semicolons |
| Journal names | Abbreviated (CASSI abbreviations) and italicised |
| Year | Bold in journal references |
| Volume | Italic in journal references |
ACS in-text citations
ACS allows three ways to cite in the text:
- Superscript number: the reaction proceeds rapidly.3
- Italic number in parentheses: the reaction proceeds rapidly (3).
- Author-date: the reaction proceeds rapidly (Lee, 2021).
With numbers, the reference list is numbered in order of first citation. With author-date, it is alphabetical.
ACS reference examples
Journal article
Author, A. A.; Author, B. B. Title of Article. Abbrev. Journal Year, Volume, First Page-Last Page. DOI: xxxx.
Book
Author, A. A. Title of Book, xth ed.; Publisher: City, Year.
Chapter in edited book
Author, A. A. Chapter Title. In Book Title; Editor, E., Ed.; Publisher: City, Year; pp xx-xx.
Website
Title of Page. Site Name. URL (accessed Month Day, Year).
Words in capitals or x's show where your details go.
Common ACS mistakes
- Mixing superscripts and author-date in one paper.
- Writing full journal names instead of standard abbreviations.
- Forgetting the bold year and italic volume in journal entries.
- Using commas instead of semicolons between authors.
Other citation styles
ACS worked examples by source type
All sources in these worked examples are fictional and were created to illustrate the format. Replace them with your real sources.
Journal article
Shah, P.; Kim, D. Sleep and Memory in First-Year Students. J. Stud. Health 2023, 18, 101-118. DOI: 10.1234/jsh.2023.018.
In-text: 1 or (1) or (Shah and Kim, 2023)
Journal article, many authors
Rivera, A.; Osei, K.; Lind, M.; Park, S. Example Catalysts for Room-Temperature Reactions. J. Example Chem. 2022, 7, 55-63.
In-text: 2
Book
Lopez, M. The Quiet Coast, 2nd ed.; Harbor Press: New York, 2021.
In-text: 3
Chapter in an edited book
Okoro, J. Tides and Trade. In Coastal Histories; Berg, A., Ed.; Northfield University Press: Northfield, 2019; pp 45-62.
In-text: 4
Web page
Healthy Sleep Habits. Sleep Facts Network. https://www.sleepfacts.example/habits (accessed 2026-10-20).
In-text: 5
Report
National Education Agency. Annual Literacy Report 2023; National Education Agency: London, 2023.
In-text: 6
Thesis
Ahmed, S. Harbour Towns and Migration, 1850-1900. Ph.D. Dissertation, Northfield University, Northfield, 2020.
In-text: 7
How to build any ACS reference, step by step
- Decide on one in-text system: superscript, italic number, or author-date.
- Write authors as Surname, Initials. separated by semicolons.
- Write the article title in title case without quotation marks.
- Abbreviate the journal name and italicise it.
- Add the year in bold, volume in italics, then the page range.
- Add the DOI at the end.
Sample ACS reference list
Here are the worked examples above assembled into a list the way they would appear at the end of an essay (numbered in order of first citation).
Shah, P.; Kim, D. Sleep and Memory in First-Year Students. J. Stud. Health 2023, 18, 101-118. DOI: 10.1234/jsh.2023.018.
Rivera, A.; Osei, K.; Lind, M.; Park, S. Example Catalysts for Room-Temperature Reactions. J. Example Chem. 2022, 7, 55-63.
Lopez, M. The Quiet Coast, 2nd ed.; Harbor Press: New York, 2021.
Okoro, J. Tides and Trade. In Coastal Histories; Berg, A., Ed.; Northfield University Press: Northfield, 2019; pp 45-62.
Healthy Sleep Habits. Sleep Facts Network. https://www.sleepfacts.example/habits (accessed 2026-10-20).
National Education Agency. Annual Literacy Report 2023; National Education Agency: London, 2023.
Ahmed, S. Harbour Towns and Migration, 1850-1900. Ph.D. Dissertation, Northfield University, Northfield, 2020.
ACS pre-submission checklist
- Every in-text citation matches an entry in the list, and every entry is cited at least once.
- The list order follows ACS rules.
- Italics, quotation marks and capitalisation match the examples above.
- DOIs are included wherever a source has one.
- Names, years and page numbers have been checked against the original source, not copied from a tool without checking.
- Your instructor's specific instructions have been followed where they differ from the general rules.
Placing ACS citations in the text
With superscripts, place the number after the relevant word or at the end of the sentence, outside the full stop and comma in many ACS journals, but follow your instructor or journal guidance. With italic numbers, place them in parentheses before the punctuation. Multiple sources can be cited together with commas (1,3) or a range (2-5).
Finding journal abbreviations
ACS uses the abbreviations from the Chemical Abstracts Service Source Index (CASSI). Search CASSI for the journal title to find the official abbreviation, and copy it exactly, including full stops. Do not invent abbreviations.
ACS in lab reports
In chemistry lab reports, cite the lab manual, any literature values you compare to (melting points, spectra) and any methods you adapted. Literature values without a citation are a common reason for lost marks.
Quick answers to common questions
Is ACS used outside chemistry?
Mainly chemistry and related fields; other sciences often use APA, AMA, IEEE or journal-specific styles.
Do I need DOIs in ACS?
Include a DOI whenever the source has one.
Frequently asked questions
What is the current ACS style guide?
The ACS Guide to Scholarly Communication, which replaced the third edition of the ACS Style Guide.
Does ACS use numbers or author-date?
Either. ACS allows superscript numbers, italic numbers in parentheses, or author-date, as long as you are consistent.
How are authors separated in ACS?
With semicolons: Lee, J.; Patel, R.; Chen, Y.
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