Epitaxial SnO 2 films were deposited on TiO 2 single crystals with various orientations by plasma enhanced atomic layer deposition (PEALD), and their structural characteristics and gas sensing properties were investigated, particularly focusing on the crystallographic orientation dependence of H 2 gas response. Dibutyltindiacetate (DBTDA) was used as Sn source, and (100), (001), (110), and (101) TiO 2 were employed as substrates for SnO 2 deposition. All the SnO 2 films were ∼90nm thick after 1000 ALD cycles and epitaxially grown on TiO 2 substrates, which were confirmed by X-ray pole figure and high resolution transmission electron microscopy (HRTEM). Differently oriented epitaxial SnO 2 films showed the different H 2 gas response and different temperature dependence of gas response. The (101) SnO 2 films grown on (101) TiO 2 exhibited the highest H 2 gas response of ∼380 toward 1000ppm H 2 /air at 400°C, which was associated with the different temperature dependence of resistance in (101) film rather than the microstructural characteristics and chemical composition compared to the other films.