Insituinfrared spectroelectrochemistry has been used to observe electrolyte/solvent breakdown processes in TBAF/acetonitrile at a platinum electrode. Anodic breakdown gives the adduct CH3CNBF3as the major product. Cathodic breakdown gives the anion of 3-aminocrotonitrile as the major product in the absence of water, and the formation of this product is a consequence of reduction of hydrogen dissolved in the metal. In the presence of water the anion of acetamide is also formed, and breakdown commences at much less negative potentials.