The aim of this paper is to evaluate numerically the effect of varying the electrochemical model and its parameters on the performance and entropy generation of a mono-block-layer build (MOLB) type geometry of a solid oxide fuel cell. Particularly, the influence of the exchange of current density, the electrical conductivity of the electrodes and the electrolyte has been studied and the prediction of the thermodynamic irreversibility by means of an entropy generation analysis is considered. The numerical analysis consider a 3-D CFD model that takes into account the mass transfer, heat transfer, species transport, and electrochemical reactions. Several numerical simulations were performed and each contribution to the local entropy generation rate was computed. The results show different... trends of the current density, temperature, species, activation loss, ohmic loss, and concentration loss along the fuel cell. Also, the results show strong variations of the local and global entropy generation rates between the cases analyzed. It is possible to conclude that the fuel cell performance and the prediction of thermodynamic irreversibility can be significantly affected by the choice of the electrochemical models and its parameters, which must be carefully selected.