Effects of resin compositions in ternary systems of benzoxazine, epoxy, and phenolic novolac resin,on processability, and thermomechanical properties of their carbon fiber-reinforced composites are investigated. At Suitable range of resin mass ratios, the ternary mixtures can provide a relatively wide processing window ranging from 50 to 200 degrees C by maintaining their low A-stage viscosity for a relatively long time which is crucial in the fiber preimpregnating process. Furthermore, relatively long shelf-life of the ternary mixtures stored at room temperature (similar to 30 degrees C) up to 270 days is obtained with minimal effect on their processability. The optimum mass ratio of B : E : P was determined to be 3 : 6 : 2, i.e., BEP362 resin. Finally, the carbon fiber composite based on BEP362 was found to exhibit Substantial enhancement in its mechanical properties. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1225-1234, 2009