Novel physically crosslinked graphene oxide (GO)-gelatin nanocomposite hydrogels were obtained by self-assembly. The hydrogels with various ratios of GO to gelatin were prepared, and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The static and dynamic rheological properties of the hydrogels were investigated, along with the underlying hydrogel formation mechanisms. The storage modulus of the hydrogels (containing 98-98.5 wt % water) reached 114.5 kPa, owing to the relatively strong physical bonding (i.e., hydrogen bonding and electrostatic forces) between GO and gelatin. Drug release tests showed that the drug release from the hydrogel was pH-dependent, with 96% of the model drug released in a neutral environment, compared to 28% released in an acidic medium. These hydrogels could have potential in pH-sensitive drug delivery. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 356-367