The selective sublimation processing (SSP) is a useful and easy method for production of semiconducting thin films via reactive sputtering for gas sensing. We have investigated the mechanism of film growth and processing for an insight into the main parameters that control the preparation methodology. A model based on diffusion equation, in the framework of a linear theory, has been proposed and compared to experimental evidences. Rutherford backscattering spectrometry has been extensively used as a tool for determination of concentration profiles in the layers. The model allowed a deeper understanding of film preparation with a physical description of the processes involved, which would open up the design of innovative nanostructured materials that rely on SSP. Titania thin films produced by this methodology and proved capable of sensing target gases of interest for many applications.