Carbon nanotubes (CNTs) were grown on TiB2 powder by chemical vapor deposition using a Co catalyst. Then, the bulk CNTs(Co)-TiB2 composite was consolidated from these in-situ synthesized powder by spark plasma sintering. Homogeneously-dispersed CNTs with herringbone-like structure composed of well-crystallized graphite were observed. The flexural strength and fracture toughness of the in-situ synthesized CNTs(Co)-TiB2 composite were determined to be 987 +/- 42 MPa and 12.4 +/- 0.5 MPa m(1/2) respectively, which were much higher than those of monolithic TiB2 and TiB2-CNTs composites synthesized by traditional ball-milling and sintering. The improvement of the composite performance was ascribed to the hybrid effect of the fully dense structure of the composite, the appropriate interfacial strength between the CNTs and the matrix, and the higher strengthening ability of well-dispersed CNTs. (C) 2017 Elsevier B.V. All rights reserved.