The present invention concerns a process for preparing an aqueous composition in the form of a gel at a given temperature. The process is characterized in that an associative water-soluble polymer constituted by a hydrophilic main chain and hydrophobic pendant groups is brought into the presence, in said composition, of at least one surfactant in the form of bilayers when it is in aqueous solution under the same temperature and concentration conditions. Compositions in the form of gels or liquids are thus obtained.