An in situ DRIFT and mass spectrometric study of catalytic partial oxidation of methane with Ir/alpha-Al2O3 has enlightened relationships between the formation of surface metal carbonyl clusters and residence time and temperature conditions. Some cluster species produced during catalytic partial oxidation were also originated during CO2 hydrogenation and CO2 reforming experiments described in previous literature. An EXAFS analysis of the catalyst precursor, prepared through a solid-liquid reaction between Ir-4(CO)(12) clusters and the reactive surface sites of alpha-Al2O3, is also included to discuss clusters structure produced at the surfaces.