Chemical sensing, as a typical application in intelligent systems, is receiving increasing attention in both industry and academia. In this context, here we investigates the sensing behaviour and mechanism of different metal oxides, hydroxides etc. towards hazardous gases like CO, CO2, NH3 etc. The present study shows hazardous NH3 gas sensing behaviour of as prepared and annealed Nickel-Cobalt double hydroxides. The results provides superior response to ammonia gas even at lower concentration of 2 ppm constitutes it as new promising gas sensing material.