The present invention concerns enantioselective preparation of sulphoxide derivatives or their salts. The method consist in performing an enantioselective oxidation of a sulphur of general formula (I) A --CH.sub.2--SB, wherein: A is a diversely substituted pyridinyl ring and B is a heterocyclic radical comprising an imidazo-pyridinyl ring, using an oxidizing agent in the presence of a titanium .sup.(IV)-based catalyst and a chiral ligand consisting of a cyclic beta or gamma-amino-alcohol, in an organic solvent, followed, if required, by salt formation with a base. The invention is useful for preparing sulphoxides useful in therapeutics.