The molecular structure and conformation of nine substituted N-benzylideneaniline R1C6H4CH=NC6H4R2 where R1=H, R2=OCH3, CH3 or Cl; R1=OCH3, CH3, Cl or NO2; R2=H; R1=NO2 R2=OCH3 and R1=OCH3 R2=Cl have been studied experimentally by FTIR spectroscopy and theoretically using the AM1 semi-empirical quantum-mechanical method. From IR data of substituted N-benzylideneaniline, a decrease in the C=N stretching frequencies were observed. There is a correlation between C=N stretching frequencies and the Hammett σR constant of substituents. The calculated values of torsional angle (θN) between the H-C=N plane and the N-phenyl ring of the compounds show that the stronger the electron withdrawing properties of the substituent, the larger the angle. There is also relationship between θN and Hammett σR constant of substituents. The dipole moments, bond order and electron density values of studied compounds have also calculated using semiemprical AM1 method.