For my thesis, I'd like to add a mchem formula to the title of a chapter. However, I cannot manage LaTeX to print it in bold. Here is the package I am using

\subsection{\ce{He^+} on Enstatite (\ce{MgSiO_3})}

This is the output I'm getting, although I would like it to be uniformly bold. I have already tried to put a \textbf in front of the \ce expressions but that didn't work. I am grateful for any help I can get on this!

1 Answer 1


You have explicitly set version=1 as a package option, which forces mhchem to use math mode for all text. That quite deliberately does not follow surrounding (text) font changes. I would strongly suggest using the latest version: version=4. You can then also omit the _ in the input for MgSiO3.

  • Thank you for your input! However, if I use versions 2,3 or 4 of mhchem the "+" next to "He" is displayed differently, it gets bigger. Is there any way to keep the small plus and still have LaTeX print the formula in bold?
    – bcserven
    Commented Sep 14, 2022 at 2:03
  • @bcserven The only change I can see is that the +, like the other symbols, now follows the surrounding font change. That's by-design, but you could force math mode for the +: \cs{He^{$+$}}.
    – Joseph Wright
    Commented Sep 14, 2022 at 6:37

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .