A pilot-scale countercurrent trickle bed reactor (TBR), packed with a water-repellent catalyst, is investigated for deuterium exchange between water and hydrogen, to be used for the production of heavy water. The reactant, i.e. heavy water, from liquid phase is stripped by the gas phase wherein, it undergoes an equilibrium limited exchange reaction with hydrogen over a solid catalyst. A two phase mathematical model is developed incorporating reaction kinetics, mass transfer resistances, and dispersion in liquid phase flow to simulate the reactor performance. Model parameters such as kinetic rate constant, mass transfer coefficient etc. were determined by independent experiments. The reactor model is then experimentally validated by performing reactions in pilot scale column. The validated model is further used to arrive at a suitable design for the desired performance.