Cuprous selenide nano-crystals were prepared using a heating-up process. The coordination solvent (oleylamine) dosage and whether or not dissolving the starting material prior to thermal decomposition effects on the crystalline phase and morphology of cuprous selenide nano-crystals were investigated. It was observed that nearly mono-dispersed Cu2-xSe crystallites with a size of about 20 nm and Cu/Se ratio of 1.73 can be obtained by pre-dissolving CuCl in oleylamine and Se powder in octadecene and reacting at 250 degrees C for 3 h. (C) 2012 Elsevier Ltd. All rights reserved.