Photochromic disazo condensation pigments have been synthesized by the condensation of 1-azaphenyl mercuric acetate-2-hydroxy-3-naphthoic acid with various benzidine derivatives and subsequent: treatment dithizone. The photochromic disazo condensation pigments have been characterized by their IR spectra and elemental analysis. The kinetic study of photochromic behaviour has been investigated by preparing films of the pigment. The pigment film on exposure to sunlight or tungsten light source of suitable wavelength showed very good photochromic effect. The film regained its original colour on removal from sunlight. The duration for return of the colour depends upon the intensity of incident light, ambient temperature, moisture content and thermal treatment of the film.