An AlxOy/Pt/AlxOy multilayer solar absorber for use in solar-thermal applications has been deposited onto copper substrate by electron beam (e-beam) vacuum evaporation at room temperature. Different samples were annealed at different temperatures in air and characterized by spectrophotometry, emissometry, heavy ion elastic recoil detection analysis (HI-ERDA), X-ray diffraction (XRD), and energy-dispersive Xray spectroscopy (EDS). The AlxOy/Pt/AlxOy multilayer solar absorbers heated up to 500 degrees C were found to exhibit good spectral selectivity (alpha/epsilon) of 0.951/0.08. However, beyond 500 degrees C the spectral selectivity decreased to 0.846/0.11, possibly due to thermally activated atomic interdiffusion profiles. HI-ERDA has been used to study depth-dependent atomic concentration profiles. These measurements revealed outward diffusion of the copper substrate towards the surface and therefore, the decrease in the constituents of the coating. The decrease in the intensity of Pt grains and formation of CuO and Cu2O phases at 700 degrees C were confirmed by XRD and EDS. (C) 2014 Elsevier B.V. All rights reserved.