The photochemical gafting HEMA onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBHV films using benzophenone (BP) or H2O2 as initiator was investigated to develop a route of grafting restricted to the surface. The effect of various parameters, such as monomer concentration, initiator, and reaction time, on grafting yield was studied and compared with results obtained when using benzoyl pet-oxide (BPO) as initiator. The morphology and structure of grafted films were characterized by Fourier Transform Infrared spectroscopy with attenuated reflexion, scanning electron microscope and Energy Dispersive X-ray Analysis. The results show that BP and H2O2 are very efficient for the grafting on the surface PHBV. The process is very fast and easy and the results are reproducible in a wide range. Photoinitiation grafted only on the surface in comparison with BPO, where the grafting is located in all the bulk of film. The films grafted by UV in presence of H2O2 are totally biodegradable when the graft level was low (less than 10%). (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 288-297, 2010