Abstract: Gelatin hardeners, suitable for use in hardening gelatin-containing photographic layers, of the formula: ##STR1## wherein: X is a member selected from the group consisting of O and S or is absent,each Y independently is a member selected from the group consisting of O, S and a bond,each R.sup.1 independently represents an aliphatic group of up to 10 carbon atoms or the two R.sup.1 groups together represent the necessary atoms to complete a 5, 6 or 7-membered ring,--NR.sup.2 R.sup.3 contains not more than 12 skeletal atoms andR.sup.2 and R.sup.3 are independently members of the group consisting of hydrogen, cyclic groups and acyclic groups or R.sup.2 and R.sup.3 together represent the necessary atoms to complete a heterocyclic ring.