Continuous hydrothermal synthesis in supercritical water (supercritical synthesis) is a method to prepare highly crystalline nanoparticles of homogeneous complex metal oxides as well as single metal oxides rapidly and continuously using supercritical water as antisolvent. Ceria-zirconia mixed oxide has widely been used as catalytic promoter due to its oxygen storage capacity (OSC). Ceria-zirconia mixed oxide with high surface area could be prepared by the supercritical synthesis, so that it also has the potential application as catalyst support due to its high surface area. In this study, ceria-zirconia mixed oxide with high surface area prepared by the supercritical synthesis was used as a support of transition metal (Mn, Fe, Co, Ni, Cu) oxide catalysts for wet oxidation of phenol. Intermediate selectivity and mineralization selectivity were investigated together with catalytic activity. Copper oxide catalyst showed the highest catalytic activity which could be explained with the surface reducibility of the catalysts. Also, copper oxide catalyst showed the highest mineralization selectivity indicating that it remarkably enhanced the deep oxidation of phenol. Ceria-zirconia mixed oxide prepared by superciritical synthesis is a promising catalyst support for wastewater treatment. Its oxygen storage capacity can assist the active element in removing organic pollutant such as phenol.