Isolating metal nanowires from a reaction mixture also containing ancillary inorganic particles distinct from the nanowires, includes: providing a mixture of metal nanowires with large particles having at least two dimensions 250 nm or more, and small particles of which the largest dimension is less than 200 nm, in the form of a dispersion in a solvent medium having a viscosity at 25° C. 10 mPa·s or more; leaving the mixture to settle out under conditions conducive to the formation of a supernatent phase including the small particles and of a precipitate comprising the metal nanowires and the large particles; isolating the precipitate, and dispersing the isolated precipitate in a solvent medium having a viscosity at 25° C. less than 10 mPa·s; leaving the suspension to settle out under conditions conducive to the precipitation of said large particles; and recovering the nanowires in the form of a dispersion in the supernatent phase.