A new approach for CuInSe2 formation by sequential electrodeposition of Cu and In-Se layers and subsequent heat-treatment with elemental selenium in Ar and Ar + H-2 flows is presented. The nature of the precursors and their evolution as a function of the selenization parameters have been studied by x-ray diffraction and x-ray photoelectron spectroscopy analysis. Sample temperature, Se-source temperature, and H-2/Ar volume ratio in the flow were the subject for optimization. A sample temperature above 400 degrees C is needed to obtain single-phase CuInSe2 films. An increase in the film crystallinity has been reached by maintaining the Se-source temperature above 400 degrees C. The introduction of H-2 in the selenizing atmosphere has proven to be unsuitable, H2Se formation must be avoided because it is more poisonous and less reactive than the elemental selenium vapor.