Zinc Oxide/Multiwall Carbon Nanotube (ZnO/MWCNT) nano sheet network is grown by an in situ hydrothermal method on glass substrate. MWCNT is added to ZnO precursors during hydrothermal process with different percentage of additive MWCNTs. Interdigitated Ag electrode is deposited on glass substrate beforehand. CO gas is used as the target gas and sensitivity of the sensors is tested with dry air as carrier gas. The sensors show considerable high sensitivity and fast response to CO at around 100 degrees C operating temperature which is promising for industrial applications. This sensor is having advantage of being small in size, very thin structure, very low working temperature, fast response and recovery time and sensitive to low ppm CO gas. Sensors with more additives MWCNTs show stronger responses to CO gas. Sensors with 2 wt% additive MWCNTs showed the sensitivity of 1.6 and sensors with 6 wt% additive MWCNTs showed the sensitivity of 2.5-5 ppm of CO gas. Samples were characterized utilizing Field Emission Scanning Electron Microscopy (FE-SEM), X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area measurement. (C) 2017 Elsevier B.V. All rights reserved.