Poly(vinyl alcohol) (PVA) and poly(N-vinyl pyrrolidone) (PVP) composite hydrogel with interpenetrating polymer networks (IPNs) was prepared by in situ polymerization and compared with pure PVA hydrogel. The prepared IPN hydrogel was characterized by infrared spectroscopy (IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The mechanical property and cell culture were also tested. The results show that PVP can chemically bond with PVA and form uniform blend hydrogel. The content of PVP can affect the structure, crystallinity, glass transition temperature (Tg), and mechanical property of the hydrogel. The Tg of the PVA hydrogel is 2.7 degrees C while the Tg of the IPN hydrogel is -37 degrees C. The IPN hydrogel has lower glass transition temperature, corresponding to better elastic properties, and has better mechanical performance on stretch and compression than PVA hydrogel. The crystallinity (Xc) of PVA hydrogel and IPN hydrogel is 65.3 and 26.3%, respectively. The DMA curves and XPS analysis suggest that PVA and PVP are well miscible on a molecular level in the IPN hydrogel. The cell proliferation trend demonstrates that the addition of PVP has a positive influence on the cell growth and the IPN hydrogel may be used as a promising biomaterial for artificial cartilage substitute. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012