The invention relates to a new process for the preparation of carboxylic acid chlorides by phosgenation of the corresponding carboxylic acid in the presence of a catalyst.This process is characterized in that the said catalyst is chosen from the compounds represented by the formulae ##STR1## in which R.sub.1 to R.sub.6, which are identical of different, denote: aliphatic, alicyclic, araliphatic or aromatic radicals,or form, in pairs, with the nitrogen atom to which they are attached or with the N-C-N group, a 5- or 6-membered heterocyclic ring.The process applies to most carboxylic acids.The acid chlorides obtained are known and used to produce radical polymerization initiators or pesticides.