en Research Paper Research Paper Present paper investigates the dissolution behavior of copper from chalcopyrite concentrate sample using cupric chloride solution in detail. Response surface modeling (RSM) in combination with d-optimal design (DOD) was utilized for modeling and optimizing the cupric chloride leaching process. At first, a quadratic polynomial model was developed for the relationship between the recovery of copper and influential factors. The predictions indicated an excellent agreement with the experimental data (with R² of 0.9399). Then, the effects of main factors including pH (1-4), liquid/solid ratio (2-7 mL/g), temperature (70-90 &deg;C), CuCl₂ concentration (6-35 g/L), and leaching time (0.5-16) were determined. The findings demonstrated that the temperature and CuCl₂ concentration were the most effective factors on the dissolution rate of copper from chalcopyrite sample, while liquid/solid ratio had the lowest impact. The recovery of copper increased linearly with an increment in the liquid/solid ratio and the decrease in the pulp pH. Additionally, the recovery enhanced by increasing the temperature and CuCl₂ concentration owing the generation of Cu&ndash;Cl complexes species and reached a plateau point and then almost remained unchanged. Meanwhile, it was found out that the recovery of copper was independent of the interaction between factors. Moreover, the optimization of leaching process was carried out by Design Expert (version 7) software and desirability function method and the highest recovery of copper was found to be about 86.1% at a pH of ~1.4, temperature of 89 &deg;C, liquid/solid ratio of 6.8 mL/g, CuCl₂ concentration of 21.79 g/L and leaching time of ~8 h.<br> &nbsp; Copper leaching,Chalcopyrite concentrate,HydroCopper® process,Cupric chloride,D-optimal design (DOD) 16 26 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-687-3&slc_lang=en&sid=1 R. Katal rashid.katal@gmail.com 1800319475328460014640 1800319475328460014640 No Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran A. Azizi azizi.asghar22@yahoo.com 1800319475328460014641 1800319475328460014641 Yes Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran M. Gharabaghi m.gharabaghi@gmail.com 1800319475328460014642 1800319475328460014642 No School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran