Films of polystyrene and styrene ionomers with various content of sodium acrylate were studied in terms of changes in surface properties after UV-irradiation or plasma action. The alterations were examined by contact angle measurements and FTIR-ATR spectroscopy. Both UV-irradiation (3h and 4h) and the plasma action (30s) induced a growth in the sample hydrophilicity owing to appearance of polar groups on the surfaces. More effective alterations of surface polarity were caused by the plasma action. However, these changes were reversible, contrary to the results caused by UV-irradiation. Photons can penetrate deeper into the sample rendering the changes more durable.