The electrochemical performance of solid oxide fuel cells (SOFCs) operating directly with pure dimethyl ether (DME), DME + air, and DME + N-2 was studied for temperatures ranging from 550 to 650 C. The power densities achieved for DME + air operation at 550 C were approximately 70 and 112 % greater than those for pure DME and DME + N2, respectively. Kinetic modeling and mass spectrometry data indicated adding oxygen (via air) to DME promoted decomposition into primarily H-2, CO, and CH4. The increased performance achieved for SOFCs utilizing the DME + air fuel mixture was attributed to oxygen promoted decomposition of DME. (c) 2005 The Electrochemical Society.