A global environmental pollution has become serious problem, due to extensive automobile density and industrialization deeds where destructive as well as poisonous gases like hydrocarbons, carbon monoxide and nitrogen oxides in the surrounding are being extremely used. Nitrogen dioxide (NO2) gas is a usual contaminant in air, in general formed through the power plants, combustion in industrial factories and automotive engines etc. As per health and safety guidelines concern human should not be in contact to 3 ppm exposure of NO2 gas for the time more than 8 hr as its poisonous character can consequence into deterioration and olfactory paralysis. Thus, it is essential to develop sensitive, cost-effective, selective, and trustworthy sensor for the finding of extremely crouch concentration of poisonous NO2 gas.A metal oxide semiconductors (MOS) such as zinc oxide (ZnO), copper oxide (CuO), tungsten oxide (WO3), iron oxide (Fe2O3), tin dioxide (SnO2), Nickel oxide (NiO) and chromium oxide (Cr2O3) etc., have been widely addressed as sensor resources for NO2 gas due to their high sensitivity, reproducible and stability in idiom of gas response. Conversely; MOS gas sensors normally have their difficulty in disgraceful selectivity, nevertheless; change in resistance of the sensor caused by gas species, which assembles it unachievable for a sensor to precisely identify the gas molecules. Such selectivity and other central gas sensing recital of chemiresistive type MOS gas sensors can be enhanced through the amalgamation of metal oxide semiconductors. Spaced out from the MOS p-type CuO and n-type ZnO are immensely concerned in gas sensing assert due to their effortless synthesis, tailorable electrochemical properties, cost-effectiveness and eco-friendly signature too.Here, a CuO nanoparticle (NPs) - ZnO nanowire (NWs) hetro-structure gas sensors have been developed by easy, catalyst free thermal evaporation (TE) technique, followed by annealing in different atmosphere such as argon and air. The crystal structural, surface morphological and gas sensing measurements of hetrostructure sensors were studied and reported. At optimized temperature of 150 °C, the hetero-structure sensors express a superior response up to 175% to concentration of 100 ppm NO2 gas. As synthesized hetro-structure sensors, responds to an enormously squat (1 ppm) disclosure of NO2 gas. Figure 1