AbstractChemically modified derivatives of the copolymeric poloxamer surfactants have been polymerised to form crosslinked, swelling hydrogels. Mixtures of derivatives of poloxamers 188 and 181 form gels which show increased swelling with increased content of the more hydrophilic poloxamer 188. The rate of release of benzoic andp‐hydroxybenzoic acids also increases with increasing content of poloxamer 188. Release rate data have been analysed in terms of the swelling controlled release model for these hydrogel