We have studied the performance of (LSCM)–Cu–yttria-stabilized zirconia anodes for the direct utilization of hydrocarbon fuels in a solid oxide fuel cell (SOFC). A significant decrease in anode polarization resistance and an increase in impedance peak frequency was observed with increasing the cell current density for , , and fuel at both 973 and . This was interpreted by considering an increase in LSCM lattice oxygen stoichiometry and a corresponding increase in electrocatalytic oxidation activity with increasing oxygen flux to the anode. A series of catalytic measurements indicates that, at a low current density (low oxygen stoichiometry), the anode reaction mechanism is dominated by hydrocarbon cracking. At a higher current density (higher oxygen stoichiometry), the reaction mechanism is dominated by total oxidation of hydrocarbon fuels on the LSCM surface to form and . This change in mechanism is confirmed by measurement of cell open-circuit voltage as a function of fuel, , and partial pressure and by analysis of the SOFC product stream. The increase in oxidation activity is attributed to an increase in nonequilibrium oxygen, relative to the anode gas, within the LSCM phase.