Abstract: A numerical model delineating kinetical process of dye cloud formation in conventional color silver halide system was designed based on diffusion and reactions of oxidized developer(QDI). The reactions,such as deamination,sulfonation and an interfacial coupling reaction of QDI with a dispersed coupler (in droplets),were involved as QDI generated on the surface of a silver halide grain spherically was diffusing in a medium layer. With some parameters,radial distribution of the formed dye,distributions of QDI concentrations vs. time and space,amount of reduced silver and dye yield etc.could be obtained from the numerical simulation.

Key words: chemical kinetics, numerical simulation, dye cloud