The catalytic hydrogenation of ethylene on Pt catalysts was simulated by a Monte Carlo model. Elementary events such as adsorption, diffusion, and desorption of the species involved (hydrogen, ethylene, and ethane) and reaction on the surface were considered. Based on comparison between experimental and calculated data no distinction has to be made between competitive and noncompetitive hydrogen adsorption sites nor has adsorbed hydrogen activation to be taken into consideration. However, steric hindrance caused by adsorbed ethylene and ethane has been included in the model. Not only was the basic physical and chemical behavior reproduced by this very simple model, but also important experimental findings such as the trend of the turnover frequency versus hydrogen pressure (P-H2) and the magnitudes of reaction orders for hydrogen and ethylene. In addition this model can predict some aspects of hydrocarbon hydrogenation not investigated experimentally so far.