Cubic boron nitride/Tungsten carbide-cobalt (cBN/WCCo) composites were fabricated at low temperature by pulse electric current sintering (PECS) using NiP as sintering additives to promote low temperature densification. Effect of cBN addition on the densification behavior, microstructure and mechanical properties of WCCo composites was investigated. It was found that near-fully dense WC/Co with 0 similar to 20 similar to vol% cBN composites could be obtained at temperatures between 1100 degrees C and 1200 degrees C under 50 similar to MPa, while no phase transformation of cBN into the low-hardness hexagonal hBN. The 20 similar to vol% cBN/WCCo sample sintered at 1100 degrees C under a pressure of 50 similar to MPa for 10 similar to min has a combination of hardness 16.5 similar to GPa and fracture toughness KIC 13.7 similar to MP.m1/2. The homogeneously dispersed cBN particles in the WC/Co composites promoted a slight increase of hardness, but a significant improvement of fracture toughness. The cBN particle bridging or deflection and pullout contribute to the high toughness.