Copper-based catalysts have been evaluated for the combined partial oxidation and steam reforming of dimethyl ether (DME) in a reformer designed to produce hydrogen for a full-scale heavy-duty truck auxiliary power unit. The experiments were conducted using gas mixtures similar to realistic operating conditions. A Pd-promoted CuZn catalyst was found to be highly selective for hydrogen production from DME at O-2/DME = 0.25 and H2O/ DME = 2.5. The catalysts were characterized using Brunauer-Emmett-Teller surface area measurement, X-ray diffraction, and temperature-programmed reduction. The copper surface area was determined by pulse chemisorption of nitrous oxide. In addition to the reforming catalyst evaluation, a startup sequence was tested, where DME was catalytically ignited and combusted over platinum or iron oxide catalysts.