A process for the preparation of fluorobenzenes of the formula I ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are equal or different and represent H, F, Cl or alkyl having from 1 to 3 carbon atoms, at least one of these radicals being fluorine, and S.sup.1 and S.sup.2 being equal or different and represent H or a group reducing the electron density at the benzene nucleus, which comprises subjecting a compound of the formula II ##STR2## in which R.sup.1, R.sup.2, R.sup.3, S.sup.1 and S.sup.2 have the aforementioned meaning to a decarbonylation at a zeolite catalyst.