I'm writing a full paper for JACS using the achemso package. I am asked to an "S" in front of the number (eg. Figure S1 or Scheme S2 etc.) in all graphics (figures, schemes etc.) in the supporting information. How could I do it?

  • Can you please add to your question a simple document showing us the document class used and the relevant packages loaded? What do you mean by "in the supporting information"? Is that some special kind of section in your document? May 14, 2013 at 13:21
  • \documentclass[journal=jacsat,manuscript=article]{achemso} <br/> \usepackage[version=3]{mhchem} % Formula subscripts using \ce{} <br/> \usepackage{color} <br/> \usepackage{graphicx} <br/> \usepackage{caption} <br/> \usepackage{subcaption} <br/> \usepackage{multirow} <br/> \usepackage{pdfpages} <br/> --- This is what I used. Thank you for your comment. :)
    – Rong Shang
    May 14, 2013 at 13:31
  • @GonzaloMedina. Sorry this is the first time I post here. The formatting is a mess. :(
    – Rong Shang
    May 14, 2013 at 13:40
  • 1
    Yes, code in comments can't be properly formatted. It's better to edit your question and to add there the code. Please see my answer below for a solution, and let me know if this is what you need. Welcome to TeX.SX, by the way! May 14, 2013 at 13:42

1 Answer 1


Since achemso uses the caption package, you can use \DeclareCaptionLabelFormat to achieve the necessary formatting:



\title{The Title}


\section{Test Section}

\caption{test figure}


enter image description here

The solution above only changes the string used in the caption label, but cross-references will be still only numeric (without the "S"). If the string used in cross-references must also have the "S" character, then, instead of defining a new caption label format, it's better to redefine \thefigure:


A similar redefinition might be also necessary for other float types.

  • Thank you sooo much, @GonzaloMedina! It works like a magic. :)
    – Rong Shang
    May 14, 2013 at 14:35
  • @RongShang You're welcome! Don't forget to accept the answer (by clicking in the checkmark to its left), if you consider it solved your problem. In case of doubt, please see How do you accept an answer?. May 14, 2013 at 15:49
  • @RongShang I added a final remark to my answer which might be useful for you. May 14, 2013 at 22:56

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