Partial oxidation of methane to synthesis gas was carried out using supported iridium catalysts. The performance of supported iridium catalysts in synthesis gas formation depended strongly on the support materials. Ir(5 wt%)/TiO2 afforded 25% conversion of methane (CH4/O-2=5) to give CO and H-2 With the selectivity of above 80% at 600 degrees C. Ir/TiO2 catalyst gave a CO-to-H-2 ratio of 2.0, as expected from the stoichiometric reaction. No carbon deposition was observed with the supported TiO2, and a constant activity was exhibited for at least 15 h, The synthesis gas yield with Ir/TiO2 catalyst was the same as supported Ph catalyst, which is reported to be the best catalyst for this reaction. The active species of Ir/TiO2 catalyst was found to be metallic iridium by XPS analyses.