Nanocrystalline　WC-Co　bulk　was　prepared　using　a　novel　route　that　combined　in　situ　reactions　and　subsequent　spark　plasma　sintering.　The　microstructure　was　characterized　by　transmission　electron　microscopy-based　precession　electron　diffraction　technology.　The　nanocrystalline　microstructure　has　a　high　WC　grain　contiguity.　The　fraction　of　Sigma　2　boundaries　increases　with　a　decrease　in　WC　grain　size.　The　effect　of　microstructure　on　the　mechanical　properties　was　analyzed　in　terms　of　the　correlations　between　Co　distribution,　Sigma　2　boundary　fraction　and　WC　grain　contiguity.　(C)　2012　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.