The quality of CuGaTe2 (CGT) thin films elaborated by close spaced vapor transport technique has been studied as a function of the source temperature (T-S), iodine pressure (P-I2) and the amount (X-Cu) of pure copper added to the stoichiometric starting material. A thermodynamic model was developed for the Cu-Ga-Te-I system to describe the CGT deposition. The model predicts the solid phase composition with possible impurities for the operating conditions previously mentioned. The conditions of stoichiometric and near-stoichiometric deposition were determined. The value of T-S must range from 450 to 550 degrees C for P-I2 varying between 0.2 and 7 kPa. Adding an amount up to 10% of pure copper to the starting material improves the quality of the deposit layers and lowers the operating interval temperature to 325-550 degrees C. These optimal conditions were tested experimentally at 480 degrees C and 500 degrees C. The X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy have proved that the addition of pure copper to the stoichiometric source material can be considered as a supplementary operating parameter to improve the quality of CGT thin films. (C) 2013 Elsevier B.V. All rights reserved.