A new class of photographic masked stabilizers is disclosed showing following general chemical formula (Ia) or (Ib): ##STR1## wherein X and Y each independently represent N or CR, R being hydrogen or lower alkyl,Z represents a lower alkyl group, a nitro group, a halogen atom or hydrogen, andM represents a positive counterion, preferably an alkali cation, ammonium or substituted ammonium.The compounds are demasked by hydrolysis under alkaline conditions. They can be incorporated in a developing solution or in a photographic material, preferably in the backing layer. They show an enhanced solvability in water compared to the corresponding unmasked stabilizers.A preferred compound is 1-(2-sulphonatobenzoyl)-5-nitroindazole trimethylamine, sodium or potassium salt.