The invention relates to a method for producing a solid nanocomposite material comprising nanoparticles of a metal coordination polymer with ligands CN, said nanoparticles satisfying the formula [Alk+x]Mn+[M′(CN)m]z− where Alk is an alkali metal, x is 1 or 2, M is a transition metal, n is 2 or 3, M′ is a transition metal, m is 6 or 8, and z is 3 or 4; said Mn+ cations of the coordination polymer being bound by an organometallic bond or a coordination bond to an organic group R2 of an organic graft, and said organic graft furthermore being chemically attached, preferably by a covalent bond, to at least one surface of a solid support, by reaction of a group R1 of said graft with said surface.