The structural characteristics of CdTe/CdS thin-film heterojunctions are investigated. The studied heterojunctions were obtained by successive thermal evaporation under vacuum onto unheated SnO2 coated glass substrates of CdS and CdTe films, respectively. The morphological and structural studies of the above mentioned heterojunction component films, in comparison with those of CdS and CdTe films, deposited separately, onto glass substrates, were carried out using transmission electron microscopy, X-ray diffraction and atomic force microscopy techniques.