Transparent fine-granular SnO2 and SnO2-Pd films (SnO2 average particle size 25-30 nm) have been obtained by annealing of tin hydroxide sols, stabilised with oleic acid. The structure of the films was investigated by TEM, ED and Mossbauer spectroscopy. In SnO2-Pd films, annealed at 800 degrees C, palladium is present as homogeneously distributed thermally stable particles (d=5-8 nm). Observed isomeric shifts of Sn-119 Mossbauer spectra suggests the presence of partially reduced tin ions, Sn2+ and Sn3+, in the films. Deeper reduction of SnO2 and formation of SnO are observed in SnO2-Pd films, annealed at 500 degrees C. Thin-film sensors based on sol-gel obtained SnO2 and SnO2-Pd are high-sensitive to different gases (H-2, CH4, NO, CO). They enable detection of CO and CH4, CO and NO selectively in mixtures by controlling of sensor’s operating temperature.