Deployment of impedance methodology for selective sensing of ammonia by silver decamolybdate is demonstrated. Using AC impedance, interaction behavior of Ag6Mo10O33 thick film towards ammonia, hydrogen and petroleum gas at 573 K and 623 K was studied. The thick film exhibited selective response down to 5 ppm of NH3 at 623 K at frequency of 14 kHz. This method is found to be superior to the conventional dc based methodology. (C) 2019 The Electrochemical Society.