Abstract: The stability of 4’-methoxy-4-diazo-diphenylamine metal double salts is investigated by IR spectroscopy, thermal analysis and evolution rate of N₂ gas from acidic aqueous solution.IR absorbanee ratio, temperature of thermal decomposition, and photo-decomposition indices are found to be in close relation with the stability of the metal double salts.The results can be explained by taking into account the electron configuration and electronegative ty of the metal atoms. The mechanism of decomposition of diazonium salts has been discussed.Some results of the performance tests of the light-sensitive films with the double salts are discussed. It has been found that the films with zinc and cadmium double salts are relatively stable. A good correlation between the decomposition temperature, thermal decompsition index and decrease in D_max of the light sensitive films has been established.