This study investigates the effects of annealing time on the optical and electrical properties of tin dioxide coatings, specifically surface resistivity and specific conductivity. The thickness of the film, as well as its density and void density, were calculated from the interference peaks. The results suggest that as the duration of annealing increases, the density of the film decreases and the void volume increases. The lack of interference peaks in the transmission spectra of films containing additives is caused by the development of dendritic structures within the films. As the annealing duration is extended to 6 h, the surface resistivity increases, resulting in a decrease in the specific conductivity of all films. As the duration of annealing increases, the surface resistivity of the films studied increases and therefore their overall quality decreases.