In this paper, the effect of the cupric and chloride ions concentrations on copper dissolution from chalcopyrite concentrate was studied in acidified media. Variables included three different concentrations of Cu²⁺ (0.5, 1.5, and 2.5 g L⁻¹), four different concentrations of Cl⁻ (0, 5, 7, and 10 g L⁻¹), two different pH values of 1 and 2, and a constant temperature of 60 °C. Results indicated that addition of Cl⁻ to the system improves copper extractions, especially at higher concentrations of Cu²⁺. Initial copper concentrations in the leaching solution did not significantly affect the copper extraction when Cl⁻ was not present. Better copper extractions were obtained at pH 1 as compared with pH 2. As the Cu²⁺ and Cl⁻ concentrations were increased, higher values of redox potential were obtained. According to the formation constants of the chloro-complexes, the predominant species in the Cu²⁺/Cl⁻ system in the studied interval were CuCl⁺ and Cu²⁺. Using a model of copper speciation in the experimental range predicted for a single copper concentration with increasing Cl⁻ concentration, the Cu²⁺ concentration decreased significantly while the concentration of the chloro-complex species CuCl⁺ increased. In the leached residue, evidence of sulfur formation was found using SEM and corroborated by XRD analysis. When chloride is present in the medium, the amounts of copper and iron in the residue decrease, confirming a positive effect of chloride on the extraction of copper from concentrate for the studied conditions.