Abstract: Carrier particles whereon a metal from the group VIII of the periodic element system is fixed are dry-mixed with particles from hydrophobic material which is simultaneously a binder and may thus bind the carrier particles together. The thus obtained mixture is subjected to an agglomeration step. The resulting agglomerates are broken. The broken agglomerates are screened and that fraction with a grain size smaller than 1 mm is pressed into a cake at a pressure of 25 kg/cm.sup.2 at the most. The press cake is rolled and catalyst particles are cut from the rolled cake. The catalyst particles are mixed with hydrophilic particles. The thus obtained mixture is used in an isotopic exchange column for separating tritium from aqueous effluents. In this column the effluents are lead in counter-current to gaseous hydrogen.