Composite Nickel graphene nanoparticles with hybrid magnetic and electrical properties were prepared. Nickel nanoparticles were tethered to the graphene through a carbon layers and were covered with an amorphous carbon layer to protect them from oxidation. Ni-graphene polyimide nanocomposites were prepared and exhibited magnetic characteristics and high electrical conductivity. The saturation magnetization of the polyimide nanocomposites increased with increasing magnetic nanoparticle content. First order reversal curve (FORC) magnetization showed a bimodal size distribution of the magnetic nanoparticles. Ultra-small-angle X-ray scattering (USAXS) of the nickel nanoparticles in Ni-graphene polyimide nanocomposites were estimated by a sphere model with bimodal size distribution. Nickel graphene nanoparticles were examined by high-resolution transmission electron microscopy (HR-TEM) where two size ranges of nickel were observed. Ni-graphene nanoparticles were well dispersed in the polyimide resin when examined by HR-TEM. Ni-graphene polyimide nanocomposites exhibited magnetic actuation when exposed to a static magnetic field. (C) 2013 Elsevier Ltd. All rights reserved.