The invention relates to a process for preparing an at least partially lithiated transition metal oxyanion-based lithium-ion reversible electrode material, which comprises providing a precursor of said lithium-ion reversible electrode material, heating said precursor, melting same at a temperature sufficient to produce a melt comprising an oxyanion containing liquid phase, cooling said melt under conditions to induce solidification thereof and obtain a solid electrode that is capable of reversible lithium ion deinsertion/insertion cycles for use in a lithium battery. The invention also relates to lithiated or partially lithiated oxyanion-based-lithium-ion reversible electrode materials obtained by the aforesaid process.