In this work a study of ZnO and Cu-doped ZnO nanoparticles obtained by chemical synthesis in aqueous media was carried out. Structural analysis gave the dominant presence of wurtzite ZnO phase forming a solid solution Zn1-xCuxO. For high Cu doping CuO phase is also present. For low Cu concentration the lattice shrinks due to Cu atoms substitute Zn atoms. For high Cu concentration the lattice enlarges due to predominance of interstitial Cu. From elemental analysis we determined and analyzed the incorporation efficiency of Cu atoms in Zn1-xCuxO as a function of the Cu concentration in the precursor dissolution. Combining structural and chemical results we described the Cu/Zn precursor concentrations r(w) in which the solid solution of Cu in ZnO is predominant. In the region located at r(w) approximate to 0.2-0.3 it is no longer valid. For Cu/Zn precursor concentration r(w) > 0.3 interstitial Cu dominates, and some amount of copper oxide appears. As the Cu concentration increases, the effective size of nanoparticles decreases. Photoluminescence (PL) measurements of the Cu-doped ZnO nanoparticles were carried out and analyzed. (C) 2014 Elsevier Ltd. All rights reserved.