In order to provide protection against extremely toxic gases Activated Carbon (AC) adsorption has long been regarded to be a useful technology in terms of gas removal. AC without chemical impregnation has been considerably less effective than impregnated ACs. AC in present use was modified with an organic amine i.e. triethylenediamine (TEDA) to enhance the physical and chemical properties of AC in order to remove specific poisonous gases. Purpose of this study was to assess the TEDA impregnated AC in terms of adsorption capability for simulant gas like SO2. Analysis was done in a properly designed setup. By using the scheme reported here, significant adsorption of toxic gas was obtained. Maximum removal capability observed by AC-4 for SO2 gas was 3.74 g/g-C and its breakthrough time was 264 minutes. Breakthrough time and adsorption capacity of AC-4 was found to be 25 times and 10 times greater as compared to raw AC. Different characterization techniques were also used to study impregnated AC. It was found that chemical adsorption was the crucial means by which TEDA impregnated AC removed the simulant gas. Langmuir model was best to represent equilibrium and adsorption kinetics follow second order model. The process was endothermic, favorable and spontaneous.