Aim of present work is design of gas sensing devices which are based on the nanocomposite of the two metal oxide semiconductors (ZnO and SnO2) and the Polypyrrole conducting polymer, using Surface Plasmon Resonance (SPR) Technique. Metal oxides are excellent choices as base materials in emerging technologies in the field of Gas Sensors. Gas sensing response characteristics of the prepared sensor were performed. Optical technique is preferred over electrical techniques for analyzing the dielectric properties and out of all techniques, Surface Plasmon Resonance (SPR) is most suitable. The theoretical simulations were done to find out the optimum thickness of ZnO and Polypyrrole composite films for sharp SPR reflectance values. Experimental studies were done to validate the theoretical studies and discussion were done about the interaction of NH3 gas with prism/Au/ZnO/Polypyrrole system. Tin oxide (SnO2), a versatile metal oxide due to its wide range of applications and its nature as an amphoteric oxide, has attracted researchers globally for many decades. The gas sensing layer in the SnO2/Polypyrrole nanocomposite multilayer structure system is used to design a sensitive and effective ammonia gas sensor device based on the phenomenon of Surface Plasmon resonance (SPR). The results obtained, highlight the usefulness of the SPR setup for the study of the Ammonia vapors interaction of the metal dielectric/Polypyrrole nanocomposite material. The outcome of these results validates the significance of SPR technique for application of interaction of surface adsorbed analytes, with the interface of dielectrics and sensing material.