In the present work, we investigated the micellization, gelation and the structure of aggregates ofthree poly(ethylene oxide)-poly(styrene oxide)-poly(ethylene oxide) block copolymers (EO12SO10,EO10SO10E10 and EO137SO18EO137, where E represents the oxyethylene unit, S the oxystyrene unit,and the subscripts correspond to the number of monomeric unit constituting the polymeric chain)in solution. We also investigated the adsorption process and the surface properties of these blockcopolymers at the air-water (a/w) and chloroform-water (c/w) interfaces. Since these copolymerspossess a more hydrophobic middle block –the styrene oxide unit, they should gives rise to moreefficient drug delivery systems, in which geometry might play a key role for drug solubilisation andcell uptake. For these reasons, a detailed characterization of the physicochemical properties ofthese copolymers is required.