The invention relates to a method for the preparation of a composition of nanoparticles of at least one crystalline metal oxide from at least one organometallic precursor. One precursor(s) which can react spontaneously to oxidation is selected; a liquid solution of the precursor(s) is produced in a solvent non-aqueous medium, and the liquid solution is placed in contact with at least one oxidant in adapted reactional conditions in order to directly result in the production of nanoparticles of crystalline metal oxide(s). The invention also relates to a composition of nanoparticles obtained in the form of a colloidal liquid solution.