Structure zone models (Movchan-Demchishin, Thornton, etc.) have been proposed to predict the morphology of metal and metal–oxide films produced by PVD or CVD processes. An original model was proposed for metal–oxide coatings made by the sol–gel process, based on a thorough experimental study of the microstructure of many coatings either obtained at INM or reported by other laboratories. The different morphologies – granular, layered, columnar – were described in terms of a parameter q=ICS/SLT, where ICS is a so-called “intrinsic crystallite size” and SLT is the single layer thickness and the homologous temperature T H =T Sintering /T Melting . The influence of these morphologies and parameters on the electrical properties of transparent conducting ZnO:Al coatings is reported.