Abstract: The influence of Ag_2SO_4,Li_2SO_4,Na_2SO_4,K_2SO_4,NH_4)_2SO_4,MgSO_4 and KF onthe evolution of O_2 and the formation of Cr_2O at Pt and PbO_2 anodes was investigated in mixedH_2SO_4-Cr_2(SO_2)_3 solutions.The kinetic data related respectively to Cr_2O formation and O_2 evolutionat Pt and PbO_2 anodes were measured by method of resolving the steady-state polarization curve.TheTafel slope of steady-state ～1g i relationships for Cr_2O formation reaction is close to 2×2. 303RT/βF,whereas for O_2 evolution it is close to 2.303 RT/βF(with β=0.5). The results indicate thatthe current efficiency for Cr_2O formation is increased by adding Ag￣+ ions to the anolyte and decreasedby adding Li￣+,Na￣+,K￣+,NH and Mg￣(2+) ions to the anolyte at Pt electrode.While on PbO_2 electrode,the current efficiency of Cr_2O formation is decreased by adding Ag￣+ and F￣- ions to the anolyte andincreased by adding K￣+ ions to the anolyte.