P.G. Department of Studies in Chemistry, Karnatak University, Dharwad-580 003, Karnataka, India E-mail : schimatadar@gmail.com Manuscript received 21 August 2009, accepted 24 August 2009 The oxidation of succinic acid by cerium(IV) has been studied spectrophotometrically in aqueous sulphuric acid medium at 298 K at constant ionic strength or 1.6 mol dm-3. A minute amount or ruthenium(lll) (10-6 mol dm-3) is sumcient to enhance the slow reaction between succinic acid and cerium(JV). The main

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... tion products are cerium(lll) and oxaloacetic acid. The stoichiometry is 1 : 4, that is[sue. acid] : [CeIV] == 1 : 4. The reaction is first order in both cerium(IV) and ruthnium(lll) concentrations. The order with respect to sue. acid concentration varies from first order to zero order, as the succinic acid concentration increases. Increase in sulphuric acid concentration decreases the reaction rate. The added sulphate and bisulpahte decreases the rate or reaction. The added product cerium(lll) retards the reaction rate. The active species or oxidant and catalyst are Ce(SO4)2 and [Ru(H2O)6]3+ respectively. Possible mechanism Is proposed. The activation parameters were determined with respect to slow step and reaction constants involved have been determined.