We report new optical and structural properties of p-type GaAs that result from the absorption of high-intensity 10.6 μm radiation. Prior to the onset of surface melting, we find that the absorption coefficient decreases with increasing intensity in a manner predicted by an inhomogeneously broadened two-level model. As the energy density of the CO2 laser radiation is increased further, the surface topography shows signs of melting, formation of ripple patterns, and vaporization. Auger spectroscopy and electron-induced x-ray emission show that there is loss of As, compared to Ga, caused by the melting of the surface. Using plain-view TEM we find that Ga-rich islands are formed near the surface during the rapid solidification of the molten layer. Auger and SIMS measurements are used to study the incorporation of oxygen in the near-surface region, and the results show that oxygen incorporation can occur for GaAs samples that have been irradiated in air.