We report the formation of cyanuric acid species at Au(111) electrodes in cyanate-containing solutions, due to the electroless trimerization of isocyanic acid. Similar experimental bands in the range between 1300 and 1900 cm− 1 are observed in Surface Enhanced Infrared Reflection Spectroscopy experiments under Attenuated Total Reflection conditions (ATR-SEIRAS) with solutions containing either cyanate anions at high concentration or cyanuric acid. The experimental frequencies agree well with those obtained from Density Functional Theory (DFT) calculations for the adsorbed cyanurate anion, bonded to the metal in a tridentate configuration, with its molecular plane perpendicular to the metal surface. ; The authors acknowledge funding by Ministerio de Economía y Competitividad (project CTQ2013-44083-P) and University of Alicante (VIGROB-263).William Cheuquepán is grateful for the award of a F.P.I. grant associated to project CTQ2009-13142.