A mathematical model of COS hydrolysis on Al2O3, with fouling of catalyst, has been developed. Kinetic studies were carried out in a fixed bed reactor under atmospheric pressure and low temperature (40-70 °C). The effects of the COS inlet concentration, temperature, and relative humidity were analyzed. Experimental results of breakthrough curves were used to obtain kinetic parameters, which accounted for effects of S deposition on the inner-face of the catalyst. The model described the experimental breakthrough curves satisfactorily and well explained the performance of COS hydrolysis in the presence of oxygen. The exothermic heat of adsorption and activation energy, assuming Arrhenius type of temperature dependence of the equilibrium constant, were determined. Activation energy of COS hydrolysis and H2S oxidation were 35.9 kJ/mol, 19.6 kJ/mol; adsorption heat of H2O and H2S on AI2O3 were 45.1 and 60.1 kJ/mol respectively. Deactivation coefficient (a) was used to quantify the behavior of COS hydrolysis at different operating conditions. The effect of relative humidity on a is significant in the relative humidity range under study. Experimental data accorded well with model data in the studied range.