This can be a method of making a high strength composite reinforcing fiber using flat GO flakes coated on a conventional reinforcing fiber. This maintains some the flexibility of the fiber and aligns the flat graphene flakes along the surface of the fiber; this dramatically increases the strength of the fiber. It also allows bonding between overlapping flakes, in contrast to flakes being uniformly dispersed in a host material that is being reinforced and dramatically increases the strength of the host material.