Adsorption and oxidation processes of cyanate (OCN) were studied on polycrystalline platinum and Pt (100), Pt (110) and Pt (111) surfaces in alkaline solution (pH = 9). On Pt (poly), Pt (100) and Pt (110), it has been found that cyanate chemisorbs dissociatively, with production of adsorbed CO. Oxidation of cyanate thus follows a pathway involving CO on polycrystalline Pt and these single crystal faces. CO has not been observed during oxidation of cyanate on Pt (111); thus another pathway, with OCN adsorbed in either flat or terminal orientation, has been identified for cyanate oxidation on platinum surfaces.