The effect of copper content on the magnetic properties of the solegel Cu-doped ZnS films is investigated. It is found that an increase in the Cu concentration leads to the degradation of the ferromagnetic signal. In order to understand this phenomenon and to determine the correlation between the magnetic, electrical and optical properties, the photoluminescence and Hall-effect measurements are performed. The dependences of the magnetic, electrical and optical properties upon Cu content are found. It is suggested that the ferromagnetic properties arise from sulfur vacancies in the ZnS (Cu-doped ZnS) thin film. (C) 2015 Elsevier B.V. All rights reserved.