Energy supply for strongly endothermic reactions like steam reforming can be provided efficiently by internal combustion in an adiabatic fixed-bed operated under periodic flow reversal. The key to an optimal process with high productivity is a periodic reheating of the fixed-bed to a favourable temperature profile avoiding hotspots by homogeneous ignition. Therefore, combustion experiments have been performed under realistic conditions. Homogeneous combustion can be suppressed by addition of an inhibitor like steam or CO2 even if hydrogen is burned; however, in reverse-flow operation, a time-variant fuel addition needs to be installed in order to limit the maximum temperature. Autothermal methane steam reforming can then be conducted with high productivity using a synthetic PSA-offgas for combustion. (c) 2006 Elsevier Ltd. All rights reserved.