How to Cite in ACS Style: A Guide for Chemistry Students and Researchers

ACS style uses numbered citations. Add a superscript number in the text where a source supports a statement, then provide the full source details in a numbered reference list. Number sources in the order they first appear. When you cite a source again, use its original number.

For example: “The reaction produced the expected compound.^1”

The American Chemical Society’s The ACS Style Guide describes the style and its reference formats (ACS Publications; ACS Style Guide). Follow your instructor’s or publisher’s requirements for your paper.

In-text citations

Place the superscript number after the punctuation that ends the statement:

The reaction produced the expected compound.^1

If you name an author in the sentence, put the citation number after the name:

Zhang et al.^2 reported a similar result.

When several sources support a statement, group their numbers. Separate individual references with commas and use a hyphen for a continuous range:

Similar results have been reported.^1,3,5–7

Each citation number refers to a source in the reference list. Assign a number when a source first appears, then use that number throughout the paper. Do not arrange the list alphabetically or give a source a new number each time you cite it.

When different sources support separate claims in a sentence, make clear which source supports each claim. Splitting the sentence can help avoid ambiguity.

Reference list format

ACS reference details depend on the source type. Use the appropriate format and check the source itself for accurate information.

Journal article

A common format is:

Author, A. A.; Author, B. B. Article Title. Journal Abbreviation Year, Volume, Page Range. DOI.

Schematic example (all fields are placeholders):

Author, A. A.; Author, B. B. [Article title]. [Journal abbreviation] [Year], [Volume], [page range]. [DOI].

Use the journal’s standard abbreviation and include a DOI when available. In many ACS reference formats, the year is bold and the volume is italicized. Check the applicable guide or publication instructions for exact formatting.

Books and book chapters

A book entry commonly includes the author, italicized title, publisher, place of publication, and year:

Author, A. A. Title of Book; Publisher: City, Year.

A chapter entry includes the chapter author and title, followed by the book title and editor details:

Author, A. A. Title of Chapter. In Title of Book; Editor, B. B., Ed.; Publisher: City, Year; pp xx–xx.

Web pages

A web reference may include the author or organization, page title, publisher, publication date, URL, and access date:

Author or Organization. Title of Page. Publisher, Date. URL (accessed YYYY-MM-DD).

Use the information available on the page and follow the guidance for your assignment or publication. An access date can help readers identify the version of the page you consulted.

Other sources

Theses, dissertations, conference proceedings, patents, and datasets have their own reference formats. Do not use the journal-article template for another source type. If details are missing, do not guess. Check the style guide for instructions on citing the source and its available information.

Formatting details to check

Author names in a reference are usually separated by semicolons. Article titles are generally set in roman type, while journal and book titles are italicized. Capitalization, page ranges, author lists, and DOI formatting depend on the source type and the applicable ACS format. Check the relevant example in the guide.

A reference manager can help organize sources, but review its output. Imported records can contain errors in names, journal titles, page details, or publication data. Confirm that each entry matches the source and the format required for your paper.

If you have not read a source directly, cite the work you actually consulted. If you rely on a review for a finding from an earlier paper, make that relationship clear in your writing. Do not list a source as though you examined it when you did not.

Before submitting, compare the citations with the reference list. Confirm that each number points to the intended source, numbering follows first appearance, and every reference entry is cited in the text.

Key Takeaways

• ACS style uses numbered citations in order of first appearance, with full references in a numbered list.
• Reuse a source’s original number when citing it again.
• Match each reference format to its source type and verify details against the source.
• Check citation placement and reference-list numbering after revisions.