The adsorption of cyanide (CN) on Ni(111) is treated using an 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 CN is able to bind to the surface either via the carbon, or nitrogen, or in a side-on geometry with very small differences in total energy (approximate to 0.1 eV). Adsorption energies at threefold, bridge and atop sites are comparable, with the fee threefold site more favorable over other adsorption sites by approximate to 0.1 eV. At the fee threefold site, adsorption energies and C-N stretching frequencies are 5.0 eV and 2150 cm(-1) for the eta(1)-cyanide-N, 4.9 eV and 1970 cm(-1) for the eta(1)-cyanide-C, and 4.9 eV and 1840 cm(-1) for the eta(2)-cyanide-C,N, respectively. Dipole moment calculations show that the bonding of CN to the Ni surface is largely ionic, while eta(2)-cyanide-C,N has more covalent character. Calculated energy barriers in going from eta(1)-cyanide-C to eta(2)-cyanide-C,N, and from eta(2)-cyanide-C,N to eta 1-cyanide-N are around 0.1 eV. Thus although CN is strongly bound to the surface (at approximate to 5 eV), within an energy range of approximate to 0.2 eV, the molecule is free to rotate to other geometries. During this rotation there are large changes in the dipole moment.