In this study, zinc oxide nanowires (ZnO NWs) coated with crystalline tin oxide (SnO2) by an ultrasonic spray pyrolysis were investigated. High resolution transmission electron microscopy analysis confirms that a continuous single SnO2 layer of about 10 nm has been coated on the ZnO NWs. Photoconductivity measurements revealed that the ZnO NWs coated with the single uniform SnO2 layer had a higher photoconductivity ratio by about a factor of 8 compared to the pristine ZnO NWs, attributed to the multi-photoexcited electrons. Under a steady radiation of UV light (lambda=325 nm), a substantial increase in the steady-state photocurrent is noticeable, suggesting that extra photoinduced charges are transferred from SnO2 to ZnO NWs.