The microwave-assisted chemical bath deposition method is used for synthesis of polypyrrole (Ppy) thin film. The structural, morphological, optical absorption and wettability properties of deposited Ppy thin films are studied using various characterization techniques. The X-ray diffraction pattern shows amorphous nature of Ppy thin film. To confirm the formation of Ppy compound, Fourier transform infrared spectroscopic study is used. The scanning electron microscopy study shows porous structure of Ppy thin film. The optical study revealed that Ppy thin film exhibits band gap of 3.5eV. The Ppy film exhibited hydrophilic nature with contact angle of 41 degrees. The Ppy films show 85% response to ammonia (NH3) gas at room temperature.