The optical properties of Ni/Al2O3, V/Al2O3, V/SiO2, V/MgO, Fe/Al2O3 and Fe/MgO composite films have been studied with consideration given to their applicability as selective solar energy absorbers. Thin films were produced by coevaporation and the microstructure examined by electron microscopy. The optical properties of Ni/Al2O3 composites, measured over the range of the solar spectrum, are in good accord with the predictions of Maxwell–Garnetttheory provided the Ni volume fraction is ≲0.2. The Ni/Al2O3films have excellent spectral selectivity for the absorption of solar radiation with a solar absorptivity of 0.94 obtained for a film produced with a graded composition. Low‐temperature emissivities of ∠0.1 have been obtained for Ni/Al2O3 on a highly reflecting metal backing. The composite Ni/Al2O3 is stable at high temperatures in air. The V and Fe composite studies have optical properties different in character from the predictions of Maxwell–Garnetttheory and are not as suitable for solar energy applications as Ni composites.