In this study, double-shell composites consisting of inner ZnO hollow microspheres (ZHS) surrounded by outer ZnFe₂O₄nanosheets were successfully synthesized. The growth of the ultrathin ZnFe₂O₄nanosheets (-10 nm) on the ZHS outer surface was carried out at room temperature via solution reactions in order to generate a double-shell configuration that could provide a large surface area. As a proof-of-concept demonstration of the design, a comparative sensing investigation between the sensors based on the asobtained ZnO/ZnFe₂O₄composites and its two individual components (ZnO hollow spheres and ZnFe₂O₄nanosheets) was performed. As expected, the response of the ZnFe₂O₄-decorated ZnO composites to 100 ppm acetone was about 3 times higher than that of initial ZnO microspheres. Moreover, a dramatic reduction of response/recover time has been achieved at different operating temperature. Such favorable sensing performances endow these ZnO/ZnFe₂O₄heterostructures with a potential application in gas sensing.