article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the scientific committee of Eurosensors 2014 Abstract The use of metal oxide single crystalline nanowires for chemical sensing of pollutant gases has been proposed as a reliable solution to ensure high sensor performance due to small size of the crystallites and good stability over long term operation at high temperature. To obtain enhanced sensing capabilities of ZnO nws, we prepared composite nanostructures based on p-type NiO and n-type ZnO NWs that combine the different physical and chemical properties of individual components. The superior functional performances are demonstrated in the current work by testing functional properties of chemical sensors towards reducing and oxidizing gases. The ZnO/NiO heterostuctures showed better relative response towards acetone and ethanol, with a decrease in response and recovery times with respect to uncoated ZnO nws. This is especially evident at 400°C and for a determined thickness of the NiO layer.