Graphene dispersions with concentrations up to 0.5 mg/mL were produced by dispersion in N,N-dimethylformamide with the aid of polyacrylic acid. Graphene oxide could also be dispersed with even higher concentration (17 mg/mL), and this advantage was used for the large-scale synthesis of graphene. The good dispersion of graphene sheets also facilitated the preparation of a new hybrid material of graphene and Fe3O4 nanoparticles, which exhibited interesting magnetic properties.