A compact reactor for natural gas steam reforming, in which hydrogen production was coupled with an internal combustor in alternate chambers, was developed and tested. Based on the target heat transfer concept, different reactor configurations in different reaction regions were specially designed to obtain uniform temperature distributions while it also effectively avoided hot spots in the reaction zones. For all of the reactor performances, the commercial natural gas (NG) was used to produce a hydrogen-rich reformate. The reactor could be easily started up and controlled steadily within 20-23 min by the flame combustion. A long-term test of 1000 h was performed to investigate the reactor's unsteady-state operation. During the performance, frequent change of NG and water in the reforming chamber contributed to 1.2 and 3.3 m(3)/h hydrogen yields. Although the temperatures in the reaction zones also fluctuated according to the performance, the corrugated metallic fins in the reactor could reduce this disturbance tendency and the temperatures at the monitoring points were maintained at 700-780 degrees C, which ensured minor fluctuation of the reformate composition.