Abstract. Kinetic investigation on ruthenium(III) catalyzed oxidation of xylose by a solution of potassium bromate in the presence of mercuric acetate as a scavenger for Br^- ion have been carried out in the temperature range 30⁰ – 45⁰C in both acidic and alkaline medium.  First order kinetics in the lower KBrO₃ concentration range tended to zero order at higher concentration was observed in acidic medium but shows first order dependence in alkaline medium. The order of reaction with respect to substrate is zero but the order with respect to Ru(III)  is one in both alkaline and acidic medium. Increase in [Cl^-] shows negligible effect while increase in [H+] shows negative effect in acidic medium but in alkaline medium Increase in [Cl^-] shows positive effect whereas increase in [OH-] shows negative effect. Negligible effect of mercuric acetate and ionic strength of the medium was observed in both media. D₂O have an insignificant effect on the reaction rate. A suitable mechanism in conformity with the kinetic observations has been proposed in both alkaline and acidic medium and intermediates have been studied for conformation.
 

 KEY WORDS: alkaline medium; acidic medium; kinetics; oxidation; potassium bromate; Ru(III) catalyzed; xylose.