In this study, the experimental and theoretical results on the molecular structures of some flavonoid derivatives (Baicalein and Naringenin) are presented. The FT-IR and FT-Raman spectra of the compounds have been recorded together for the first time between 4000-400 cm(-1) and 3500-5 cm(-1) regions, respectively. The molecular geometry and vibrational wavenumbers of the compounds have been also calculated in their ground states by using ab initio HF and DFT/B3LYP functional with 6-31G(d,p) basis set used in calculations. The calculations were utilized to the C(1) symmetries of the molecules. All calculations were performed with Gaussian 98 software. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Scale factors have been used in order to compare how the calculated and experimental data are in agreement. Theoretical infrared intensities were also reported. Copyright (c) 2008 John Wiley & Sons, Ltd.