CuGaSe 2 thin film absorbers were deposited on molybdenum coated glass substrates by open tube chemical vapour deposition (CVD) techniques. The absorber films have been characterized with X-ray diffraction, surface morphology, electrical and optical studies. Solar cell structures of the type Mo/CuGaSe 2 /CdS/ZnO/Ni has been fabricated from the absorber thin films. Thin film absorbers as well as solar cells from them has been characterized with X-ray absorption spectroscopy in different environments and at various temperatures. XAS investigations have been performed due to their value in the study of the local structure of the heterogeneous compounds. X-ray absorption near edge structure of various components present in the system under various environments and at reaction temperatures has been determined. The thermal stability of the grown layers as well as the solar cell structures has been evaluated from the XAS studies. XAS data of the gas/solid reaction and the stability of the solid at different temperature ranges were monitored with the corresponding reaction rates. The stability of the cells in different environmental conditions, like in air and vacuum has been studied in detail. The influence of sodium-containing substrates on the properties of the developed films and the solar cell structures has been discussed.