In this work, hierarchucal porous SnO₂/Zn₂SnO₄nanospheres were succesfully prepared via a facile one-step hydrothermal method with subsequent calcination process. Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed in order to investigate the structural and morphological properties of the as-prepared composites. The results showed that the SnO₂/Zn₂SnO₄composites were cpmposed of many porous nanospheres with a uniform diameter of about 500 nm. Moreover, the as-prepared products were used as sensing material for the fabrication of gas sensor. The sensing performance of the sensor was systematically evaluated, and the sensor exhibited excellent ethanol-sensing property. The optimum operating temperature was 250 degrees C with a reponse of 30.5 toward 100 ppm ethanol. Also, the sensor showed good selectivity, stability and a low detection limit of 0.5 ppm (response 1.4). The good sensing performance of SnO₂/Zn₂SnO₄nanospheres can be attibuted to the porous structure as well as the heterojunction formed between SnO₂and ZnSn₂O₄.