[en] A double-layer SnO₂/ZnO gas sensor was produced by utilization of SnO₂ and ZnO thin films. Top layer consisted of SnO₂ produced by a sol-gel controlled-annealing technique. Bottom coating consisted of ZnO thin film precipitated by two-stage chemical deposition (TSCD) from an aqueous zinc containing solution. Both top and bottom coatings were analyzed by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and electron dispersive elemental analysis (EDAX). Auger electron spectroscopy (AES) was also used to investigate the growth of tin oxide films on zinc oxide films and their interface. Gas sensitivity of the SnO₂/ZnO double layer was determined by electrical sheet resistance measurements. Although sensitivity was slightly reduced by double-layer formation, selectivity and stability were considerably improved by combination of the two thin layers. The existence of an interfacial transition layer between SnO₂ and ZnO and stabilization mechanism of the SnO₂/ZnO double layer were rigorously investigated in this research