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The investigations presented were aimed at a description of the structure of the adsorbed layers of polyethylene glycol (PEG) on the surface of Al 2 O 3 . This was obtained from measurements of the adsorption heat of PEG macromolecules as well as of 1,2-dimethoxyethane (C 4 H 10 O 2 ) and tetraethylene glycol dimethyl ether (C 10 H 22 O 5 ), i.e. low-molecular weight compounds constituting the monomers forming the PEG chain. The results allowed the fraction of polymer segments bonding directly to the Al 2 O 3 surface to be estimated. Other information obtained from calculations based on the Scheutjens–Fleer theory included the distribution of chain segment conformations as trains, loops and tails, together with a determination of some structural changes and the sizes of PEG macromolecules as they moved from the bulk solution to the solid phase surface. The thickness of the adsorbed macro-molecular polymer layers on the alumina surface was also determined. All these data enabled an approximate description to be made of the polymer chain structure at the Al 2 O 3 –polymer solution interface.