The optical properties of nickel pigmented anodized aluminium obtained by AC voltage and by periodic-reverse current impregnation have been compared. A solar selective absorbing surface is obtained from about the same threshold nickel content (gamma(Ni) congruent to0-60 g/m(2)) Moreover in both cases, the impregnation faradic yield at the threshold nickel content is the same, whereas the structural parameters of the impregnated layers were different compared to the structural parameters of the initial DC anodic porous layer. (C) 2004 Elsevier B.V. All rights reserved.