An efficient and convenient ruthenium catalysed method for a regiospecific H/D exchange using D₂O is described. Organic moieties such as pyridine, oxazole, imidazole, pyrazole, ester, ketone and carboxylic acid have been found effective directing groups in this transformation. In addition, the deuteration of the enantiopure (S)-Ketoprofen leads to the incorporation of three deuterium atoms with retention of molecular chirality.