There is provided a process and system for producing carbon fiber products. The process can involve deasphalting a heavy hydrocarbon feedstock, which can contain native asphaltenes, to produce a solid asphaltene particulate material, which can be further treated to produce the carbon fiber products. In some implementations, the solid asphaltene particulate material can be extruded in the presence of a polymer. In some implementations, the solid asphaltene particulate material can be chemically treated with a chemical agent including a Lewis acid, an oxidizing agent and/or a reducing agent before extrusion. In some implementations, the process can further produce activated carbon fibers.