School of Studies in Chemistry, Jiwaji University. Gwalior Manuscript received 24 October 1978, revised 7 August 1980, accepted 29 October 1980 Iodination of some aliphatic ketones catalysed by hydrogen form of the resins Dowex-50W x 8 and Amberlite IRC-50 has been studied in ethanolic solutions. The overall process obeys first order rate law. The rate is independent of iodine concentration, but dependent on the quantity of the resin or the hydrogen ion concentration in the resin phase. Process of stirring and its rate does not affect the rate of overall process of resincatalysed iodination. Rates decrease with decreasing dielectric of the system studied by changing the solvent type. The effect of temperature on rate has also been studied and thermodynamic parameters evaluated. The rate controlling step in this heterogeneous process has been suggested to be the internal reaction at the site of the hydrogen ion in the resin matrix.