A study of the unsteadiness problem of the ignition of static premixed gases that contain CH4 and steam by a catalytic hot sphere and a noncatalytic hot sphere were conducted, and a comparison between calculated and experimental results was done in the paper. The catalytic reforming reaction of CH4 with steam on the surface of the sphere produced a small amount of H-2, CO and CO2, at the same time there occur oxidizing reactions of CH4, H2 and CO in the space. Both experimental and calculated results show that a small quantity of H-2 produced by catalytic reforming reaction can greatly reduce the ignition temperature. In traditional catalytic combustion precious metals is applied to catalyse oxidizing reaction between oxygen and fuel to reduce ignition temperature. In this paper, a study on a 'indirect' catalytic combustion is conducted. The cheap catalytic material of Ni with rare earth is used and reforming reaction between steam and fuel is catalyzed, so hydrogen is generated on the surface of hot sphere and utilized to improve combustion. Calculation indicates that the high reactivity and high diffusivity of H-2 remarkably affect ignition. (C) 2002 Published by Elsevier Science Ltd.