Abstract The disc column designed by S tephens and M orris  is used to study the rates of absorption of chlorine from air into solutions of 2-ethyl-hexene-1 in carbon tetrachloride. The olefin bulk concentration C B is varied from zero to 0·034 lb. mol per ft. 3, the reaction rate constant k c in the ratio 20 : 1 by varying the concentration of the catalyst (iodine) from zero to 0·001 lb. mol per ft. 3, the ratio of the bulk concentration of the olefin C B to the concentration of dissolved chlorine at the interface C i from zero to 280. The fractional increase in the liquid film coefficient due to chemical reaction varies from zero to 19, and was found to be : where k L is the liquid film coefficient and k′ L is the coefficient for physical absorption at the same liquor rate, and C C is the concentration of iodine, lb. mol per ft. 3. Additional data are presented for the gas film coefficients of the disc column, based on the rates of evaporation of water and of carbon tetrachloride.