The effect of the power discharge on the surface properties of thin films deposited from hydroxyethylmethacrylate plasma was evaluated by X-ray photoelectron spectroscopy and contact angle measurement. Surface energetics parameters were measured by model acidic or basic test liquids and discussed according to the theories of acid-base or electron donor/electron acceptor interfacial interactions. Results show that the power discharge has a marked effect on the acid-base properties of the plasma-deposited films and, as a consequence, on the interactions of the latter with the surrounding environment.