Systems consisting of epoxy resin and phenol-cardanol-formaldehyde (PCF) were prepared. The thermal characterization of the systems, investigated by thermogravimetry analysis, indicated that the increase of PCF content improves the thermal stability. Chemical resistance as well as mechanical properties of their carbon-fiber composites were also determined. The matrix-fiber interfacial study by scanning electron microscopy showed that the higher the PCF amounts in the system products, the better the interfacial bonding.