As discussed in the literature review section, it was anticipated that fibers would provide an ideal path for electron transport through the material. In order to inspect the influence of fibers on bipolar plate properties, three types of conductive carbon fibers were used in this research. The first type, Polyacrylonitrile (PAN)-based chopped carbon fiber, available from Fortafil® Fiber, was used to improve the electrical and thermal conductivity and the tensile strength of the resin. This fiber is 3 mm in length and 7 μm in diameter. Next, PAN-based milled carbon fiber (AGM-99), from Asbury Graphite Mills Inc., was combined with the chopped carbon fiber to study the effect of fiber size on electrical conductivity. The milled carbon fiber is 7-9 μm in diameter and 150 μm in length. The last type is produced by Gina New Materials Public limited company. It is a conductive carbon nanofiber with a 50 - 200 nanometer outside diameter and a 0.5 - 3 nanometer inside diameter. The fiber lengths were 10 - 70 μm. To sum it up, three carbon fibers used in this research are Fortafil® Fiber, AGM-99, and carbon nanofiber.