We investigate the initial oxidation and interface formation of cubic silicon carbide for the silicon rich β-SiC(100) 3×2 surface reconstruction by high resolution synchrotron radiation-based soft x-ray photoemission spectroscopy. The surface is exposed to low doses of molecular oxygen ranging from 1 up to 10 000 L, at surface temperatures from 25 to 500 °C. Significant formation of SiO2 is found for the surface at room temperature, with the rate of oxidation increasing with temperature. Valence band data and Si 2p core level spectra show that even at low exposures, significant oxidation is taking place, with a surface reactivity to oxygen much larger than for silicon surfaces. The oxidation products, which are grown at very low temperatures (⩽500 °C) include SiO2 as a dominant feature but also substoichiometric oxides Si+1, Si+2, Si+3, and significant amounts of mixed oxide products involving C atoms (Si–O–C).