We study the effect of various operating parameters such as temperature, molten carbonate/carbon ratio, and the type of Ni thin layer inserted between the matrix (electrolyte support) and carbon green sheet on the electrochemical performance of a 100-cm(2) class direct carbon-molten carbonate fuel cell (DC-MCFq. In addition, we attempt to understand the oxidation behavior of carbon in the wet carbon anode (the composite of carbon and molten carbonates) of the DC-MCFC. We find that in the DC-MCFC, CO is produced via a two-electron transfer reaction [C(s) + CO3-2 -> CO2(g) + CO(g) + 2e(-)] and is further oxidized with CO3-2 [CO(g) + CO3-2 -> 2CO(2)(g) + 2e(-)] under closed circuit voltage conditions, indicating that CO is responsible for determining the DC-MCFC performance. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.