Abstract: Viscous, homogeneous and thermoreversible gels containing polymer chains are obtained by a process in which a solution of a prepolymer or polymer which contains at least one free acid group at each chain end in a non polar solvent selected among the aliphatic, alicyclic and aromatic hydrocarbons having a dielectric constant of less than about 3 is reacted at room temperature with a stoechiometric amount, based on the acid group content of the polymer, of a metal aliphatic alkoxide so as to neutralize all the free acid groups and a sufficient amount of the non polar solvent is distilled for removing, in a substantially quantitative manner, the aliphatic alcohol formed by said reaction.