The relative efficiency of a number of gases for the collisional deexcitation or chemical reaction with the singlet excited oxygen atoms O(1D2) was studied by a competitive technique. Excited oxygen atoms were produced by the photolysis of nitrous oxide at 2139 Å and of ozone at 3132 Å. The order of the relative efficiency of the foreign gases is [Formula: see text] in the photolysis of nitrous oxide and [Formula: see text] in the case of ozone. These trends are consistent with the previous results.