In this research, the effects of support materials and silver (Ag) loading on catalytic NH3 combustion properties were studied. Among the Ag supported on various metal-oxide materials, Ag/Al2O3 exhibited high catalytic NH3 combustion activity and high N-2 (low N2O center dot NO) selectivity. The combustion activity is closely associated with the Ag dispersion which is estimated using the O-2-H-2 titration technique. Thus, highly dispersed Ag nanoparticles on supports play a crucial role in the low-temperature light-off of NH3, implying that the support materials significantly affect the Ag dispersion. Although Ag/Al2O3 with higher amounts of Ag loading tended to exhibit higher combustion activity, the optimum Ag loading was found to be approximately 10 wt.%. At the optimum Ag loading concentration, Ag/Al2O3 performed well during the catalytic NH3 combustion reaction. The local structures of the catalysts were investigated via transmission electron microscopy, X-ray absorption fine structure and gas adsorption techniques. After an NH3 combustion reaction at a temperature of 900 degrees C, Ag/Al2O3 slightly deactivated because of the sintering of metallic Ag nanoparticles and the decreased surface area.