The effect of photographically active substance, like polyvinylpyrrolidone (PVP), on the rate of mass-transfer processes has been investigated in course of Ostwald-ripening of AgBr and Agl. The influence of PVP is determined at the interface processes of ionic crystals in the presence of various concentrations of PVP in the system, AgBr-Br-82- and AgI-I-131-. Since a very low supersaturation lies during Ostwald-ripening therefore under these conditions very low concentration of substance is very effective which adsorbs on the surface of AgBr and AgI crystals and reduces the rate of mass-transfer processes, which can be quantitatively measured by means of radiochemical measuring technique.