The partial oxidation of methane to synthesis gas over an alpha-Al2O3- and gamma-Al2O3-supported Rh catalyst has been studied at atmospheric pressure using in situ DRIFTS between 823 and 973 K. A surface intermediate species with IR band at 2000 cm(-1), correlating with the CO formation, was observed during the partial oxidation. DRIFT spectra of adsorbed CO at 323 K were used to study the state of Rh during the partial oxidation. The state of Rh at 973 K is proposed to be a matrix of metallic rhodium with clusters of partially reduced oxide phase with isolated Rh+ atoms dispersed on the support. Rh oxide with Rh+ cations is the state of Rh during partial oxidation of methane at 823 K.