Polyethersulfone (PES) ultrafiltration membranes were modified by radical grafting with the aid of redox initiators to create new functional groups on the surface. Methacrylate-based monomers were used. The modified membrane surfaces were characterized by FTIR-ATR spectroscopy to detect chemical changes during modification. In addition to the common adsorption bands of carbonyl groups typical for all grafted polymers, the FTIR spectrum displayed new absorption bands in the region of aliphatic stretching vibration of the modified PES membrane (2921-2875 cm(-1)), a region lacking absorption bands in the spectrum of the original membrane. It was also shown that the ATR technique enables recognition of the adsorption of albumin on the surface of the membranes. Preliminary results indicate, that spectral techniques such as subtracting and deconvolution could be applied in order to recognize the conformation of the adsorbed albumin.