Copper indium gallium diselenide (CIGS) nanoparticles are one the promising materials for solar cell technology applications. In this study, CIGS nanostructures were synthesized using a solvothermal method. By adding different ammonium salts, the synthesis time could be reduced by up to 2 h compared to the routine solvothermal method. The effects of ammonium halides on the synthesis process and on particle growth were investigated. Structural properties and size information of the synthesized nanoparticles were obtained by X-ray diffraction and transmission electron microscopy. The CIGS particles were found to be tetragonal with average sizes ranging from 20 to 100 nm. The optical band gap of these structures was found 1.38 and 1.46 eV. Shortening the synthesis time of dispersed CIGS nanoparticles could be interesting for the development of cost-effective or non-vacuum technologies.