Activated carbon adsorbs arsine in an inert atmosphere by physical adsorption and chemisorption. The physically adsorbed arsine desorbs readily at room temperature, which must be taken into consideration when activated carbon is used to remove arsine from effluent gas. Chemisorption is facilitated by copper and chromium present on the carbon surface as oxides. During chemisorption the arsine reduces both oxides. Upon exposure to air an exothermal oxidation reaction occurs reverting the copper and arsenic to their oxides but leaving the chromium sites in their reduced Cr3+ state.