A three-dimensional (3D) analysis has been developed and applied to obtain performance characteristics of a molten carbonate fuel cell (MCFC) of complex geometry. The equations are solved to obtain the velocity, temperature, pressure, and concentration distributions in the cathode/anode channel. The channel with uniformly distributed trapezoidal supports, is approximated by an anisotropic porous medium, and the effective permeability and conductivity are obtained by separate three-dimensional finite volume method (FVM) calculations for a single periodic module. The current density distribution for a given cell voltage is calculated iteratively by coupling it to the local chemical reaction rate. Thus, the current-voltage relation can be successfully obtained. Here, the cell characteristics for various operating conditions are presented and discussed. The calculation is carried out by increasing the electric load until the fuel-depleted region appears on the electrode surface. This procedure is capable of predicting essential cell features and may be used in finding the optimal cell design and/or operating conditions. Copyright (c) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.