An expression is obtained for the energy band bending eφsH on the surface of the SnO2 film in the clean air + hydrogen mixture. It is assumed that the value of eφsH depends not only on the surface charge density of adsorbed oxygen ions O¯, but also on the negative charged hydroxyl groups (OH¯). The results of the analysis of the dependences of eφsH on the hydrogen concentration {mathrm{n}}_{{mathrm{H}}_2} and the absolute humidity of the gas mixture obtained during the operation of the sensor in the thermo-cyclic mode are presented. A method for the determining {mathrm{n}}_{{mathrm{H}}_2} in the examined gas mixture is proposed. The method based on the dependence of eφsH on the hydrogen concentration established during the calibration of the sensor is proposed. The dependences of the energy band bending on the SnO2 surface at {mathrm{n}}_{{mathrm{H}}_2} = 0 and the conductivity of the sensor on its temperature during the heating period are discussed.