The molecular conformation, ground state molecular vibrations and force field of propionamide have been determined at the Hartree-Fock level using the basis sets 6-31 + g* and 6-31 ++g**. The potential energy surface of propionamide was investigated by the ab initio method with full geometry optimization. The trans CCCN conformation of propionamide, with methyl group in the staggered conformation to the CO group was found to be more stable than all the other conformations. The vibrational spectral analysis has been carried out for trans staggered conformer of propionamide and its C- and N-deuterated molecules. The present results arc compared with previous studies on the structure and vibrational spectra of propionamide and discussed. (C) 2002 Elsevier Science B.V. All rights reserved.