Catalytic hydrothermal reforming (CHTR) of water-soluble organics from biomass pyrolysis was studied aiming at simultaneous production of combustible gas and clean water (containing little to no organics) from the water phase of bio-oil. Reforming of the feedstock with a total organic carbon concentration (TOC) of 10 000 ppm was performed at a temperature and pressure of 350 degrees C and 20 MPa, respectively, over microporous-carbon-supported catalysts of Ni, Co-Ni, Cu-Ni, Fe-Ni, Mo-Ni, and Zn-Ni that were prepared by reference to a reported procedure. The Ni catalyst (NiC) was the most active among the above catalysts, while allowing for refractory compounds, such as acetone, to survive, with a TOC as high as 160 ppm. CHTR of model compounds revealed that acetic acid and acetol, which were most abundant in the feedstock, were important precursors of acetone. Impregnation of Pt into NiC improved the catalytic activity, especially toward reforming of acetone. The reforming of the feedstock over Pt/NiC at 350 degrees C and 20 MPa successfully reduced TOC to 6 ppm. Maintenance of such high activity was confirmed by a test with a 24 h duration.