The effect of current collectors of molten carbonate fuel cells (MCFCs) was studied through three-dimensional computational fluid dynamics and experiments. Three types of current collectors such as a sheet with sheared protrusions and perforated sheets were employed and performances of MCFCs were compared. A current collector structure with a large gas open area to electrodes improves diffusion characteristics between electrodes and gas flow channels. As a result, differences of gas mole fractions between gas flow channels and electrodes were decreased. Finally, Nernst loss and cathode polarization loss decreased, and the performance was enhanced. Using these results, current collector structures for improved performance and long-term operation were discussed. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.