Kinetics of hexavalent chromium reduction to trivalent chromium in a fixed bed of scrap bearing iron spheres was investigated under different conditions of initial concentration of a synthetic solution of acidified potassium dichromate, solution flow rate, bed height, iron spheres diameter, and solution temperature. the activation energy of the reaction was found to be 4.51 kcal/mol which shows that the reaction is diffusion controlled. The mass transfer coefficient of the reaction was related to other parameters by simple equations. Implications of the present results for treatment of industrial wastewater containing Cr such as metal finishing industry effluents are noted.