Nickel-based catalysts have been widely tested for reforming undesired tar and methane from hot biomass-derived syngas. However, nickel catalysts readily deactivate through the adsorption of sulfur compounds in the syngas. We report a new regeneration process that can effectively regenerate sulfur-poisoned Ni reforming catalysts. This process consists of four sequential treatments: (1) controlled oxidation at 750 degrees C in 1% O-2, (2) decomposition at 900 degrees C in inert gas, (3) reduction at 900 degrees C in 2% H-2, and (4) reaction at 900 degrees C under reforming condition. This 4-step regeneration process might have advantages over the conventional steam regeneration process.