A study of the influence of some growth parameters, the gradient of temperature between source and substrate and introduction of oxygen in the growth chamber, on the optical properties of CdTe thin films grown by Close Space Vapor Transport (CSVT) is presented. This study was carried out by means of photoluminescence (PL). The combined effect of the temperature gradient and oxygen in the growth chamber on the crystalline quality of CdTe thin films were analyzed. Important changes in the photoluminescence spectra were observed. A decrease of the intensity of the excitonic PL band is observed, as oxygen concentration increases. This accounts for an increase in the defect density due to the presence of oxygen. (C) 2003 Elsevier Science B.V. All rights reserved.