In this work, novel semiconductor sensors were developed for detecting high pre-explosive concentrations of H2 (0.1–2.5 vol%) with high selectivity and stability. The sensors were based on thin (∼100 nm) nanocrystalline SnO2 films produced by magnetron sputtering of dispersed Pt and Pd layers deposited on the surface and addition of 13–14 at% Pt in the bulk. Studies on their nanostructure, composition, electrical properties, and gas-sensitive characteristics were carried out. X-ray photoelectron and Raman spectroscopies revealed that in the process of stabilizing annealing in Pt/Pd/SnO2:Sb,Pt film platinum introduced into the bulk segregates on the surface of the SnO2 microcrystals in the form of Pt° metal clusters and dispersed Pt2+ ions. The dispersed Pt2+ ions form bonds with lattice oxygen and contribute to the overlap of conduction channels. In the sensor subjected to annealing at =723 K and =873K, the optimal situation is realized when under the action of low (n < 0.1 vol%) H2 concentrations, the condition 2d0 = dM is satisfied and G1/G0 = 9–12. In the range of 0.1–2.5 vol% H2, narrowing of the space-charge region favors the formation of a conducting layer, and at 2d0 ≤ dM there is a sharp increase in the values of the responses to G1/G0 = 220–250 at 2.5 vol%.