It is known that ceric ions are reduced into cerous ions when ceric sulfate Solutions are irradiated by y rays in the presence of sulfuric acid. In this work we have found that the amount of cerous ions produced depends on the concentration of sulfuric acid. The inital yield of cerous ions decreases from 3.08 to 2.35 when the acid concentration increases from 0.4 N to 1.6 N. The amount of ceric redu¬ced was not proportional to the total dose and G(Ce+3) decreased with decraesing (Ce+4) /(Ce+3) ratios. Both deaerated stannous and stannic Solutions were found to be affected by y rays. The stannic yield was 1.23 when stannous Solutions were irradiated, while a stannous yield of 0.29 was determined in irradiated stannic Solutions. Stannic ions were found to affect the radiolysis of ceric sulfate Solutions. In irra¬diated Ce (SO4)2+1.6N H2SO4 Solutions containing up to 40 mN SnCl4,the cerous yield decreased continuously from 2.35 to 1.80. When the SnCl4 concentration increases further, however, the cerous yield goes up gradually and after reaching the original value at 60 mN SnCl4, continues to increase at a lover rate. Ferric ions have the same effect as the stannic ions on the radiolysis of ceric sulfate with the only difference that the value for the minimum of G(ce+3) was lower (1.5). The doses were measured spectrophotometrically using the Fricke dosimeter system. In each case a reaction mechanism is suggested explaining satisfactorily the expe- rîmental results presented in this work.