The present invention relates to a method for the preparation of a functionalized nano size transition metal oxide or sulfide particle comprising the steps of (a) providing a ternary solvent system comprising a polar solvent, a non-polar solvent and an intermediate solvent allowing miscibility of all three components; (b) providing a mixture of a transition metal salt and a ternary solvent; (c) providing a mixture of a suitable source of oxide or sulfide and the ternary solvent; (d) providing a mixture of a non-polar end capping agent and the non-polar solvent; (e) mixing the mixtures; and (f) recovering the resultant functionalized nano size transition metal oxide or sulfide particle. The invention further relates to non-polar end capped nano sized transition metal oxide or sulfide particle so produced and the use of such particles.