CuSe and CuInSe2 nanoparticles were synthesized through the aqueous solution process using NaBH4 solution as a solvent and subsequent heat-treatment. Not only the synthesized nanoparticles, CuSe and CuInSe2, but also spray-coated thin films prepared by using CuSe and CuInSe2 were characterized by XRD, SEM-EDS, TGA and UV-Vis spectroscopy. CuSe nanoparticles with a plate-like shape, which were confirmed by XRD and SEM, were directly prepared by a reaction of a mixture of CuCl2 and Se in the aqueous solution of NaBH4 at room temperature. Cu-In-Se compounds were obtained through the reaction of CuCl2, InCl3, and Se in the aqueous solution of NaBH4, were consisted of the mixture of CuSe(x) and In hydroxides, and were transformed into CuInSe2 with a chalcopyrite structure by a heat-treatment at 300 degrees C.