The ground state fundamental inter-molecular vibrational frequencies of seven different doubly hydrogen-bonded mixed dimers involving 2-pyridone (2PY) have been predicted by different quantum chemistry calculations. Calculations have been performed by different DFT functionals with several basis sets and by the ab initio MP2/6-31G** level. The reliability of these calculations to predict the inter-molecular vibrations has been tested by comparing the experimentally measured and theoretically predicted values. Such vibrations have been measured by dispersed. fluorescence (DF) spectroscopy. The comparison shows that the B3LYP/6-31+G**, B3LYP/6-311++G** and MPWB1K/6-31+G** calculation predicted frequency values are in excellent agreement with the observed values and also to those predicted at MP2/6-31G** level of calculation. (C) 2009 Elsevier B. V. All rights reserved.