The effect of various impregnation parameters on the structural features and optical properties of solar absorbing nickel pigmented anodic alumina coatings has been studied. The impregnation starts from a threshold voltage. A correlation between microstructural features and the optical properties of these coatings has been established. Stable coating with low emissivity (0.14 at 70 degrees C) and high solar absorptivity (> 0.90) have been prepared by anodizing in a phosphoric acid solution.