In this paper, the prototype of a circular molten carbonate fuel cell (MCFC) built in the laboratories of FN SpA Nuove Tecnologie e Servizi Avanzati is analyzed using a tridimensional computational fluid dynamic (CFD) model. The prototype is the result of FN and Politecnico di Torino activities developed for the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) within the framework of Ministry of Economic Development, MSE-ENEA. This model considers heat, mass and current transfer as well as chemical and electrochemical reactions. The results show that some inhomogeneous distributions in the reactants, causing nonoptimal use of the reactant surfaces. An effective way to improve the distribution in current density consists in tracing tree shaped channels on the surface onto the distribution porous medium. In this paper, Y shaped channels are adopted to improve the distribution of gas within the fuel cell and consequently to enhance the performance of the original design of the fuel cell. In addition, the configuration of the outlet of the anodic compartment is also investigated in order to further increase the performance of the fuel cell. The geometrical parameter identifying the topology of distribution channels are chosen accordingly to the constructal theory. The results show that significant improvements can be achieved. Power density is increased of about 6% when the tree-shaped channel is adopted. If a double anodic inlet is also considered, the enhancement in the power density is of about 11% with respect to the initial configuration.