Effect of underlayer on reduction of graphene oxide (GO) by atomic hydrogen annealing (AHA) was investi-gated using microwell substrate with holes of um order. In AHA, atomic hydrogen is generated on a heated tungsten mesh through a catalytic cracking reaction of H2 gas. The X-ray photoelectron spectra showed that the GO film was reduced by AHA at 170 °C. The Ni underlayer affected the reduction of GO films. The intensity ratio of the D and G bands indicates that reduction is less likely to occur with suspended GO than with supported GO.