The vibrational spectroscopic and theoretical investigation of some diketo hydrazone derivatives; (2Z)-2-[2-(4-methylphenyl)hydrazinylidene]-1-(naphthalen-2-yl)butane-1,3-dione(NBTMH),(2Z)-2-[2-(4bromophenyl)hydrazinylidene]-1-(naphthalen-2-yl)butane-1,3-dione (NBTBH),and (2Z)-2-[2,4-(phenyl)hydrazinylidene]-1-(naphthalen-2-yl)butane-1,3-dione (NBTBFH) were made in this study. Theoretical investigations of these compounds includes conformational, NBO and vibrational analyses to see the most stable structure, possible hydrogen bondings and chemical bond diversities of the compounds, respectively. The potential energy surfaces of the compounds were obtained by DFT method regarding the selected degree of torsional freedom, which was varied from 0o to 360o in 18o steps.The geometries of the compounds were optimized through conformational analysis followed by the minimum energy conformer. Possible hydrogen bonds were searched by NBO analysis. The vibrational frequencies were calculated using the optimized geometry (bond lengths, bond angles), the atomic masses, and the force constants as the input. The atomic radii and the electronegativities of the compounds were also used as the input to calculate IR and RAMAN activities. Wilson’s GF Matrix method was used for the calculation of vibrational frequencies and the activities. The experimentally measured vibrational spectra were elucidated through theoretical calculations.