The hydrogen-deuterium (H-D) exchange reaction between trimethylamine borane (TMAB) and deuterium oxide taken up by a sulfonate cation exchanger, Dowex 50-X2 in the D+ form, was carried out in columns under dynamic conditions. A first pass of a 0.1 M solution of TMAB through a Dowex 50-X2 ion exchanger, swollen in D2O, gives > 90% conversion into TMAB-d3. A second pass of the enriched solution through a fresh resin produces 100% pure deuterated product zone. Kinetic studies of consequential deuteration of 0.1 M TMAB solutions in CCl4 with Dowex 50-X2 in the D+ form under batch conditions show that the effective rate of isotope exchange is directly proportional to the relative amount of D2O in the resin phase.