In this research, Zinc oxide (ZnO) nanostructures were synthesized by low cost hydrothermal method. The grown ZnO nanostructures had a dispersed distribution with nanowire morphology and the specific surface area of about 7 m2.gr-1 which they have crystalized in hexagonal wurtzite structure. ZnO nanowires/polyvinyl alcohol network (ZP) on the epoxy glass substrate with cu-interdigited electrods coated and it used as a solid state sensor of carbon dioxide gas (CO₂) at environmental conditions. The gas sensing properties of ZP sensor were examined toward different CO₂ concentrations (0.037-0.15 vol%) and also various relative humidity at room temperature. The highest response and lowest response time were reached 2.2 and 58.5 sec toward 0.15 vol% CO₂ concentrations at 30% and 90% relative humidity, respectively. The effect of relative humidity investigated on the sensor response and it displayed that ZP sensor response has been decreased with increasing relative humidity at room temperature. Moreover, the study of the functionalized sensor's selectivity toward air components has shown our hand made sensor has a appropriate CO₂ selectivity than other gases.