The potential energy surfaces for the formation of glycine from HCN and H2O were determined from CBS-QB3 calculations. After the formation of a HCN trimer, amino malononitrile, amino malononitrile mono amide (3) was formed by a water addition reaction. Two pathways were found for the subsequent reaction, 3 + 2H(2)O -> glycine + HNCO + NH3. One pathway involving an amino ketone was much more favored than the other pathway involving glycinamide. Addition of a water molecule as a catalyst greatly enhanced steps occurring by hydrogen rearrangement. (C) 2017 Elsevier B.V. All rights reserved.