The partial oxidation of methanol for the production of hydrogen was investigated in both a fixed-bed microreactor and in a thermogravimetric analyzer (TG-FTIR) from 180 degrees C to 250 degrees C using a commercial Cu/ZnO/Al2O3 catalyst. In the microreactor, a hot spot in the undiluted catalyst bed of 4 K and 32 K was observed at 180 degrees C and 220 degrees C, respectively. Methanol conversion was strongly accelerated between 180 degrees C and 220 degrees C. In the TG-FTIR experiments, the reduced copper was completely oxidized to cuprite, Cu2O, with increasing time-on-stream in the presence of oxygen and methanol (O-2/MeOH = 0.5) at 180 degrees C. The selectivity to formaldehyde increased in the same manner as the catalyst was oxidized to cuprite. In contrast, at 250 degrees C the catalyst remained completely reduced for the same O-2/MeOH ratio. Two main reaction pathways are proposed explaining the influence of the copper oxidation state on the product distribution. (C) 2008 Elsevier B.V. All rights reserved.