The conformational landscape of the simplest dipeptide formylglycine (FG) and its vibrational spectra were studied by B3LYP and MP2 methods and matrix isolation FTIR spectroscopy. Sixteen minima have been found on the potential energy surface. The most stable conformer is characterized by the planar structure, a stretched backbone and a cis COOH group. The calculated gas phase abundance at 333 K for two most stable FG1c and FG4a equals ca. 88% and 8%, and the remaining conformers have a negligible population. The presented FTIR results allow unequivocal identification and characterization of FG1c in nitrogen and argon matrices while other species are not experimentally observed. (C) 2009 Elsevier B.V. All rights reserved.