The invention concerns the use as catalyst for transforming carbamates of compounds corresponding to the general formula (I): --Sn (X) (X') wherein: X' is selected among chloride, bromide, iodide, thiocyanate radicals, sulphonate radicals, advantageously perfluorinated on the carbon bearing the sulphonate function; X is selected among the values of X' and among radicals of formula Y-Z; Y is selected among the chalcogen groups, advantageously light (that is oxygen and sulphur); Z is selected in the group consisting of trisubstituted tin, monosubstituted zinc, and the oxygenated acid radicals after ignoring the OH function. The invention is applicable to the coating industry.