The purpose of this study is to prepare novel carbon-supported Ni (Ni/C/Al2O3) catalysts by the sol-gel method and to perform the hydrothermal gasification of phenol water as a model of wastewater. Catalysts were prepared by the combination of aluminum tri-sec-butoxide (ASB) and tartaric acid as an organic template and the addition of active metal, nickel nitrate hexahydrate at the preparation of catalysts. After calcination under the nitrogen atmosphere, the larger amounts of active metal species were built at the carbon skeletal in the catalysts. Introduction of tartaric acid dispersed metal Ni with high loading on carbon derived from ammonium tartrate. Hydrothermal gasification was performed under the following conditions: 350 degrees C, pressure of 20 MPa, phenol water of 2-20 g/L, and LHSV of 48 h(-1).16N63C21A catalyst, which represents 16 wt.% Ni, 63% carbon in tartalic acid, and 21% Al2O3 at the preparation of the catalyst, showed the highest activity and the highest carbon balance between feed and products within 8 h among all the Ni catalysts. The activity of each catalyst increased with the elapse of time and the phenol conversion reached 100 % under the condition and phenol concentration of 2 g/L. No deactivtion was observed. (C) 2014 Elsevier B.V. All rights reserved.