Government College, Jhalawar; L.B.S. College, Jaipur; Gyanjyoti College, Srikaranpur; Government College, Kota; eoovernment College, Sawai Madhopur; Maharshi Arvind College of Engineering, Jaipur; Department of Chemistry, University of Rajasthan, Jaipur-302 004, India Manuscript received 1 October 2002 The surface-catalyzed autoxidation of sulfur(IV) in acetate buffered suspensions of Co2O3 obeys the kinetic rate law (A), \(-d[S(IV)] \over dt\) = (k3 + k4) [H+]-1 [S(IV)] [Co2O3] (A) In unbuffered suspensions, the rate law (B), at constant pH, is obeyed, \(-d[S(IV)]\over dt\)= (k7 [Co2O3] [S(IV)] (B) The reaction is not inhibited by ethanol, and this ruts out the operation of a radical mechanism. The suggested mechanism implicates the absorption of both O2 and sulfur(IV) on Co2O3 particle surface. The electron transfer within the surficial complex is responsible for the oxidation of sulfur(tIV).