The miscibility and hydrogen bonding interaction in the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(4-vinyl phenol) [P(3HB-co-3HH)/PVPh] binary blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The DSC results indicate that P(3HB-co-3HH) with 20 mol % 3HH unit content is fully miscible with PVPh, and FTIR studies reveal the existence of hydrogen bonding interaction between the carbonyl groups of P(3HB-co-3HH) and the hydroxyl groups of PVPh. The effect of blending of PVPh on the mechanical properties of P(3HB-co-3HH) were studied by tensile testing. (c) 2007 Wiley Periodicals, Inc.