Advances in nanoparticle technology led to powerful low-cost thin film techniques. Together with the established selenization method, these techniques open new possibilities for low-cost solar cell production that does not require expensive vacuum deposition systems. The chemical conversion (selenization) of nanosized precursor materials into CuInSe2 (CIS) and Cu(In,Ga)Se-2 compounds and microstructural properties of these layers have been investigated. Three categories of nanoparticles, namely metal-oxides, metal-selenides and elemental metal particles were selenized in selenium vapour. Using two different reactor designs, the influence of the selenium vapour pressure was investigated. While oxide and selenide precursors show limited sintering and chemical conversion, dense CIS layers with large grains (similar to1-2 mum) were obtained with metal precursors. (C) 2003 Elsevier Science B.V. All rights reserved.