Ab initio methods of the density functional theory and pseudopotentials were used for studying the structure, electronic states, binding energy and separation energy of Co layers on the WC(100) surface. It has been found that the first monolayer repeats the geometry of the WC(100) surface with the same value of the lattice constant. Comparison of three cases – A) Co atoms are above C atoms; B) Co atoms are above W atoms; C) Co atoms are above the symmetry centers between WC pairs – shows that the A case is an energetically preferable one. The second Co monolayer also repeats the fcc-cubic WC geometry, however the distance between the first and second Co layers is less than the distance between planes in the WC cubic crystal. All Co layers are ferromagnetic ones with magnetic moments of 0.87–2.41μ B dependently on the case. The density of states (DOS) for the WC/Co system looks like the superposition of those for bulk fcc-WC and free Co layers.