The invention relates to a process for the preparation of dispersible colloidal systems in the form of nanocapsules whose wall consists of a polymer obtained by the polycondensation of two monomers, .alpha. and .beta., and whose core consists of a substance B, characterized in that: (1) a first liquid phase is prepared which consists of a solution of monomer .alpha. in a solvent or solvent mixture and contains one or more surfactants and the substance B in solution or suspension; (2) a second liquid phase is prepared which consists of a non-solvent or non-solvent mixture for the monomer .alpha. and contains the monomer .beta. and one or more surfactants, the solvent or solvent mixture of the first phase being miscible in all proportions with the non-solvent or non-solvent mixture of the second phase; (3) the first phase is added to the second, with moderate agitation, to give a colloidal suspension of nanocapsules, agitation being maintained until the monomers .alpha. and .beta. have completely polymerized; and (4) if desired, all or part of the solvent or solvent mixture and non-solvent or non-solvent mixture is removed to give a colloidal suspension having the desired concentration of nanocapsules.