The effect of various anodization parameters on the structural features and optical properties of solar absorbing nickel pigmented anodic alumina coatings has been studied. A correlation between the microstructural features and the solar selectivity of these coatings has been established. Stable coatings with low thermal emittance, ≈0.06 (at 100°C), and solar absorptance ⩾0.90 have been prepared by anodizing in a phosphoric acid electrolyte. Addition of H 2SO 4 in the anodizing bath leads to an increase in the α and ε values of the film due to the formation of a thicker and alumina rich anodic film. By using a mixture of H 3PO 4 and H 2SO 4, α and ε values can be varied over a wide range of 0.90⩽ α⩽0.96 and 0.06⩽ ε (100°C)⩽0.46.