A proprietary in situ chemical vapor deposition (CVD) process was developed to grow a layer of pyrocarbon on carbon paper preform for proton exchange membrane fuel cells (PEMFC). The carbon paper preform is continuously manufactured by dry method. The characteristics of the carbon paper such as surface morphology, polarized light characteristics, and cross-section morphology were characterized using electron microscope, polarized light microscope, respectively. Fuel cell performance of the carbon paper was evaluated using single cell with hydrogen/air at various relative humidity (RH) conditions. The carbon paper with in situ growth of pyrocarbon showed significant improvement in lowering in-plane electrical resistance as well as fuel cell performance at dry condition. The carbon paper as seen under scanning electron microscope showed excellent surface morphology with pyrocarbon connecting carbon fibers tightly by CVD process.