Compounds of the formula (I), wherein L.sub.1, L.sub.2, L.sub.3 and L.sub.4 independently of one another are hydrogen or an organic substituent; R is for example C.sub.1-C.sub.20alkyl, C.sub.5-C.sub.12cycloalkyl, C.sub.2-C.sub.20alkenyl, substituted C.sub.1-C.sub.20alkyl; X is O, S, NR.sub.a or NCOR.sub.a; R.sub.a is for example hydrogen or C.sub.1-C.sub.20alkyl; and Y is an inorganic or organic anion; are suitable as photolatent acid generators. ##STR00001##