Internal reforming of ethanol fuel was investigated on high-performance metal-supported solid oxide fuel cells (MS-SOFCs) with infiltrated catalysts. The hydrogen concentration and internal reforming effects were evaluated systematically with different fuels including: hydrogen, simulated reformate, anhydrous ethanol, ethanol water blend, and hydrogen-nitrogen mixtures. A simple infiltration of Ni reforming catalyst into 40 vol% Ni-Sm0.20Ce0.80O2-δ (Ni-SDCN40) and fuel-side metal support leads to complete internal reforming, as confirmed by comparison to simulated reformate. The performance difference between hydrogen and fully-reformed ethanol is attributed entirely to decrease in hydrogen concentration. High peak power density was achieved for a range of conditions, for example 1.0 W cm−2 at 650 °C in ethanol-water blend, and 1.4 W cm−2 at 700 °C in anhydrous ethanol fuel. Initial durability tests with ethanol-water blend show promising stability for 100 h at 700 °C and 0.7 V. Carbon is not deposited in the Ni-SDCN40 anode during operation.