1. Presence of specific chemical adsorption of phosphine on active charcoal with additives is an essential, although not a sufficient, condition for initiation of the process of catalytic oxidation of phosphine. 2. On catalytic charcoal the most firmly chemisorbed molecules of phosphine are only very slowly oxidized by oxygen at room temperature. 3. The cuprous form of copper appears to be responsible for initiation of catalytic oxidation of phosphine. 4. At elevated temperatures the surface of the charcoal itself, without additives, acts catalytically in oxidation of phosphine by atmospheric oxygen. 5. In absence of atmospheric oxygen, and at elevated temperatures, phosphine reacts with oxygen bound to the catalyst AP-2, to give oxides of phosphorus and water. Desorption of these products leaves a surface which adsorbs gaseous oxygen with exception avidity. 6. The first stage of chemisorption of phosphine is the formation of a phosphine-oxygen complex at the catalyst surface. 7. The process of catalytic oxidation of phosphine by gaseous oxygen at the surface of active charcoal containing copper oxides involves formation of intermediate compounds, with very rapidly alternating stages of reduction and oxidation of the catalyst. The catalyst is copper oxides at room temperature, while at elevated temperatures the charcoal surface itself can act as a catalyst, without additives.