Synthesis of materials with unique properties or with a high chemical selectivity is presented as a competitive application domain for concentrated solar energy with respect to laser or plasma systems. To illustrate the general arguments recent experimental data are presented in three domains (1) surface hardening of steel, super hardness of 1000 Hv is obtained without tensile peak at the interface between treated and non treated material (2) oxides nanopowder processing, pure oxide powders and composites are obtained by vapo-condensation with typical size in the range 10-100 nm (3) fullerenes and nanotubes synthesis, a selectivity of 20% for fullerenes is achieved (ratio of fullerenes to soot mass), more recently single wall nanotubes are processed at pressure 450hPa. These results obtained with 2 kW solar furnaces are commented in the view of solar process scalingup.