In this paper, we analyse the growth by MOCVD of CdTe on glass substrates using in situ post-growth annealing. First, in order to perform a systematic study, polycrystalline layers of CdTe were deposited by MOCVD on glass substrates. The structure and morphology of the layers was investigated as a function of different growth parameters, temperature, VI/II precursor molar ratio and substrate position on the susceptor. An activation energy of E-k = 20.7 kcal/mol was obtained from the experimental data. In order to better understand the process and the effects of different growth parameters, a numerical model that simulated the gas flow in the reactor, was developed. Secondly we analysed the effect of in situ (i.e., inside the reactor) post-growth annealing. Layers with large grains have been produced with this procedure. The samples have been characterised by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. This characterisation shows structural changes induced by the annealing process and allows one to establish a correlation between those changes and the experimental conditions of the thermal process. (C) 2003 Elsevier B.V. All rights reserved.