A method for preparing a composition of metal nanocrystals from at least one organometallic precursor in a solvent medium in the presence of a PEG ligand, including a carbon chain, at least one end of which is functionalized by a coordination grouping including at least one hetero atom, and having at least one [OCH2CH2]n grouping, n being an integer higher than 1, so as to be soluble both in the solvent medium and in water. The water-compatible and organic-compatible composition of metal nanocrystals thus obtained is also described.
