Bulk CuInSe2 samples were rapidly synthesized from the reaction sintering of Cu2Se and In2Se3 to study the effect of sintering process on the microstructure and the corresponding physical properties of solar absorber materials CuInSe2. It was found that the phase purity and grain grown highly depend on sintering condition, and the optical band gap increases gradually with sintering time. The resistivity of 600 degrees C-sintered CuInSe2 first decreased then increased due to not only phase purity but also grain growth with increasing sintering time. The resistivity of 700 degrees C-sintered CuInSe2 monotonously increased only due to the grain growth. The significantly lower resistivity of the 700 degrees C-sintered CuInSe2 indicates effective photoelectric conversion behavior. (c) 2012 Elsevier Ltd. All rights reserved.