This paper describes an investigation of the adsorption of CH,I on a KI-impregnated carbon and the influence of competitive adsorption on the process. A gravimetric method was used to study the equilibrium capacity and kinetics for the adsorption of CO2 and CH,I in the presence of He, and CH,I in the presence of CO2 on the carbon. The results of these experiments were compared with those obtained from measurements carried out using a McBain spring apparatus to obtain the equilibrium uptake of CH,I vapour on the KI-impregnated carbon at 293 K. The adsorption kinetic results covering the range 275-333 K show that the rates of adsorption are only weakly dependent on the temperature. The apparent activation energies for adsorption of CO, and CH,I in the presence of He, and CH,I in the presence of CO, were 20.0 + 1.1, 6.5 + 0.3 and 10.0 k 0.5 kJ molt I, respectively. The rates of adsorption of CH,I in the presence of CO, were about half the corresponding rate of the adsorption of CH,I in the presence of Hd. However, the equilibrium capacities were very similar in both cases. Adsorption exneriments carried out over a CH,I martial pressure range, 3.08-38.5 kPa in CO, showed that the initial I _ adsorption rate constant was linearly dependent on the CHJ concentration. The-results are discussed in terms of competitive adsorption in the CH,I-CO* system.