Neutral copper sulfide clusters were analyzed using the Coalescence Kick global optimization method to explore their potential energy surface minima combined with a DFT approach at the B3LYP/def2-TZVP level. This allowed us to locate the ground state configurations and low-lying isomers. Ionization energies, electron affinities and HOMO-LUMO gaps were studied for the ground state configurations to develop a deeper understanding on the semiconductor nature. The calculated HOMO-LUMO gaps are in the energy range of 1.3-33 eV, which make (CuS)(N) clusters suitable candidates in the current search of novel nanomaterials for renewable energy sources, specifically in the photocatalysis field. (C) 2013 Elsevier B.V. All rights reserved.