A surfactant assisted facial hydrothermal process has been employed for the synthesis of rutile and wurtzite phase SnO₂ and ZnO nanoparticles, respectively, confirmed by X-ray diffraction studies. High resolution transmission electron microscopy studies revealed the formation of ∼15 and 20 nm of SnO₂ and ZnO nanoparticles, respectively, whereas, the structural analysis was done via Fourier transform infrared (FTIR) and Raman spectroscopy studies that suggested the minor doping of surfactant and surface adsorption of environmental oxygen. The gas sensing response of the prepared nanoparticles has been measured in ammonia environment and the sensing responses of the SnO₂ and ZnO nanoparticles are found to be 4.53 and 3.96%, respectively, at 46 ppm of ammonia. The mechanism of interaction of ammonia with metal oxide nanoparticles has been investigated through FTIR and Raman spectroscopic measurements performed in ammonia environment.