Ruthenium and gadolinia-doped ceria (Ru-CGO) composite nano-crystalline thin film anodes are demonstrated for the first time in self-supported micro-solid oxide fuel cells (mu SOFCs) for direct methane utilization, targeting development of microstructurally stable anodes under operation. Nano-composite thin film anodes are synthesized by co-sputtering from Ru metal and CGO oxide targets. Detailed electrical, crystalline and microstructural analyses were carried out on composite films to characterize properties as a function of Ru/CGO relative fraction. Microstructural stability of the composite film is compared to Ru metal film from conductivity and grain size behavior during 500 degrees C thermal treatments. Stress-relaxed composite thin film anodes were developed on self-supported mu SOFCs with yttria-stabilized zirconia thin film electrolytes and porous platinum cathodes. mu SOFCs were tested with room temperature humidified methane as fuel and air as the oxidant, exhibited an open circuit voltage of 0.97 V and a peak power density of 275 mW cm(-2) at 485 degrees C. Microstructural stability of Ru-CGO composite anodes relative to metal electrodes is discussed. The results suggest a general approach to synthesis of functional metal-oxide nano-composite thin films for electrodes in fuel cells and related energy conversion devices. (C) 2012 Elsevier B.V. All rights reserved.