The electroabsorption (EA) spectrum was analyzed in terms of the orientational order of tris(8-hydroxyquinolinato) aluminum(III) (Alq(3)) Molecules, where the orientational order parameter < P(n)(cos theta)> (theta: the tilt angle of molecule; P(n): nth Legendre polynomial; <>: thermodynamic average) was used to quantify the anisotropic orientational order of Alq3. It was shown that the EA intensity is a function of S(1) and S(2) at the modulation frequency omega, whilst it is a function of S(2) at the second-harmonic frequency 2 omega. The EA spectrum for the vacuum deposited Alq(3) was obtained from the optical transmittance measurement. The results suggested that the spontaneous polarization of Alq(3) is generated in the evaporated films. (C) 2009 Elsevier B.V. All rights reserved.