Crystallographic orientation relationships and interfaces in directionally solidified WC-W2C eutectoids are investigated by electron microscopy and electron back-scattered diffraction. The WC-W2C eutectoids are prepared by a laser surface processing method, which unidirectionally melts and resolidifies ceramic powder substrates. Lamellar-type microstructures are observed in all samples with preferred nominal growth directions of []WC//[]W2C along the solidification direction. The majority of interface habit planes are found to be (0001)WC//(0001)W2C. The interfaces are found to be semicoherent, with a misfit Burger's vector of 1/3[]. An intermediate layer is identified at the interface and is associated with a change in the stacking sequence of the close-packed (0001) tungsten planes.