A process for producing nano-scaled graphene plates with each plate comprising a sheet of graphite plane or multiple sheets of graphite plane with the graphite plane comprising a two-dimensional hexagonal structure of carbon atoms. The process includes the primary steps of: (a) providing a powder of fine graphite particles comprising graphite crystallites with each crystallite comprising one sheet or normally a multiplicity of sheets of graphite plane bonded together; (b) exfoliating the graphite crystallites to form exfoliated graphite particles, which are characterized by having at least two graphite planes being either partially or fully separated from each other; and (c) subjecting the exfoliated graphite particles to a mechanical attrition treatment to further reduce at least one dimension of the particles to a nanometer scale, <100 nm, for producing the nano-scaled graphene plates.