A wood hydrolysate derived hemicellulose-rich fraction was functionalized with L-lactide oligomers through a ring opening polymerization mediated grafting-from reaction. The graft copolymer was designed to act as a compatibilizer in hydrolysate/poly(L-lactide) (PLLA) blend films. The PLLA addition improved the tensile behavior of the hydrolysate matrix and this effect was enhanced further by the addition of minor amounts of the synthesized compatibilizer. With only 1% (w/w) of compatibilitzer the compatibility between the components and the homogeneity of the resulting films were greatly improved with an increase of strain-at-break with up to 400%. The oxygen permeability of the blend films was markedly reduced with the addition of wood hydrolysate, compared to the barrier properties of pure PLLA, an effect that is not significantly compromised when compatibilizer amounts are kept small. (C) 2011 Elsevier Ltd. All rights reserved.