In order to elucidate the mechanism of ethanol oxidation, a simple cylindrical diffusion-surface reaction was developed on a platinum disk electrode. An ethanol electro-oxidation mechanism was proposed, in which electrochemical reactions proceed without adsorption of any electro-oxidation products (C2 type) on the surface. After the simulation of the proposed mechanism, it was seen that the model can explain ethanol electro-oxidation behavior without any surface CO formation. The simulation of the mechanism indicated that the formation of acetaldehyde through the oxidation of bulk ethanol is the rate determining step between 0.6 and 0.75 V vs. RHE. After 0.75 V vs. RHE, the formation of surface acetate through bulk ethanol becomes the rate determining step. According to the proposed oxidation model, around 0.7 V vs. RHE, acetaldehyde coverage becomes the major surface species, and acetate formation starts around 0.7 V vs. RHE. Surface species profiles of the proposed model show that C2 type species play an important role in ethanol electro-oxidation.