The performances of a coupled reactor in which a steam reformer and a catalytic combustor weremounted simultaneously had been investigated and compared. The combustible offgas exhausted from the anodeof SOFC and MCFC were utilized as heat sources for the endothermic steam methane reforming. The catalyticcombustion was used in order to burn the combustible offgas. Thermal energy released by the catalytic combustionis directly transferred to the reformer surrounding the combustor. The various operational conditions such as fuelutilization rate, steam to carbon ratio, amount of catalysts, fuel cell loads were changed. And operating variableswere comprehensively identified by sensitivity analysis. The fundamental results from this experimental study showthe potential abilities of the coupled reactor. Therefore the results will be of help to design and manufacture themore better coupled reactor in the future.