The present invention provides a conductive epoxy resin composition which comprises an epoxy resin, a hardener, a hardening accelerator and a carbon material comprising expanded graphite, wherein the hardening accelerator comprises at least one member selected from the group consisting of phosphine hardening accelerators, phosphonium hardening accelerators, amine hardening accelerators and imidazole hardening accelerators, and is contained in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the hardener. Also disclosed are a process for producing the epoxy resin composition, and a separator for fuel cells and a process for producing the same using the epoxy resin composition.