The absorber-reflector tandem configuration is used for the realization of a selective absorbing surface for the photothermal conversion of solar energy. The infrared reflector consists of a stainless steel substrate, covered or not with a W or Mo thick film. The visible absorbing function is realized by a thin, low cost, Fe-A1,0, cermet film. The cermet films are prepared by R.F. co-sputtering onto a rotating stainless steel substr'te. The target consists of a circular Al203 plate covered with small discs, the concentration varying with the Fe disc number. The optical properties of the thin Fe-Al203 are studied as a function of the Fe volume fraction from 0.2 to 0.9. The dielectric function is calculated from the reflectivity and transmittivity measurements in the 300-50.000 nm spectral range. The films exhibiting the required selective properties : high absorptivity in the visible, high transparency in the infrared, are selected. A sandwich, composed of a thin Al203 antireflecting film, the cermet film (with adequate thickness and composition) and the reflecting substrate, exhibits a good selectivity for the photothermal conversion at low and middle temperatures.