In H2S containing solutions, the reduction of protons with a buffer effect contributing to the transport of protons at the steel surface, is not sufficient to explain the cathodic polarization curves obtained on 316L stainless steel. An additional electrochemical reaction was observed and was attributed to a direct H2S reduction. A numerical model is presented with these hypotheses and a good agreement is found with the experimental data presented in a previous paper. With this model it is also possible to present the concentration profiles of the different species involved in the cathodic process. (c) 2013 Elsevier Ltd. All rights reserved.