The interaction of hydrogen cyanide (HCN) and hydrogen isocyanide (HNC) with Ni(111) is studied by using ab initio embedding theory. The Ni(111) surface is modeled as a three-layer, 28-atom cluster with the Ni atoms fixed at bulk lattice sites. The present calculations show that both HCN and HNC bind to the surface in an end-on geometry with the molecular axis perpendicular to the surface. Tilting either the H atom or the H-C bond or the H-N bond away from the surface normal destabilizes the system. The side-on bonded HCN and HNC with the C-N bond parallel to the surface are energetically less stable than the corresponding end-on bonded species. The calculated adsorption energy of the end-on HCN is 18 kcal/mol with the fee 3-fold site favored over other sites by about 1-3 kcal/mol. The end-on HNC binds to the surface at the atop site with adsorption energy of 11 kcal/mol. The calculated adsorption energy for the side-on bonded HCN is only 7 kcal/mol. The side-on bonded HNC species is; found to be unbound by 12 kcal/mol on Ni(lll). Calculated C-N stretching frequencies are 2200 cm(-1) and 2100 cm(-1) for end-oh bonded HCN and HNC and 2105 cm(-1) and 1530 cm(-1) for the side-on bonded HCN and HNC, respectively. Dipole moment calculations show that the bonding of HCN to the surface is relatively more ionic than HNC.