A series of recyclable NiO/NaBr catalysts were prepared by supercritical hydrothermal synthesis for hydrogen production from formaldehyde steam reforming. Combined with XRD, N2 adsorption/desorption, SEM, XPS, H2-TPR, in situ DRIFTS and other characterization techniques, the phase structure, specific surface area, microstructure, element valence, redox properties and steam reforming reaction transient of NiO/NaBr catalysts were analyzed. Results showed that 1%~5% NiO/NaBr catalysts efficiently produced hydrogen. 2%NiO/NaBr showed the best hydrogen selectivity about 104% at 450 ℃, and its formaldehyde conversion was close to 100%. The hydrogen production performance after one-time regeneration could return to the fresh level. The NiO/NaBr catalyst had dense surface structure and small surface area ( < 1 m2·g-1), which broke the limitation that small-surface-area catalyst was difficult to obtain high catalytic activity. The steam reforming of formaldehyde was a surface rapid reaction process. NiO was reduced to Ni without affecting the catalytic activity. NaBr could not only adsorb formaldehyde and form polyformaldehyde, but also help the catalytic maintain great low temperature redox properties and hydrogen production performance.