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WO₃−SnO₂ composite nanorods were synthesized by combining hydrothermal growth of tapered tungsten trioxide (WO₃) nanorods and sputter deposition of thin SnO₂ layers. Crystalline SnO₂ coverage layers with thicknesses in the range of 13−34 nm were sputter coated onto WO₃ nanorods by controlling the sputtering duration of the SnO₂. The X-ray diffraction (XRD) analysis results demonstrated that crystalline hexagonal WO₃−tetragonal SnO₂ composite nanorods were formed. The microstructural analysis revealed that the SnO₂ coverage layers were in a polycrystalline feature. The elemental distribution analysis revealed that the SnO₂ thin layers homogeneously covered the surfaces of the hexagonally structured WO₃ nanorods. The WO₃−SnO₂ composite nanorods with the thinnest SnO₂ coverage layer showed superior gas-sensing response to 100−1000 ppm acetone vapor compared to other composite nanorods investigated in this study. The substantially improved gas-sensing responses to acetone vapor of the hexagonally structured WO₃ nanorods coated with the SnO₂ coverage layers are discussed in relation to the thickness of SnO₂ coverage layers and the core−shell configuration of the WO₃−SnO₂ composite nanorods.