The effect of temperature on absorption and fluorescence spectra of 4-aminobenzonitrile (ABN) in 1,2-dichloroethane is studied for temperature ranging from 296 K to 343 K. The analysis of absorption and fluorescence band shift on the basis of Bilot and Kawski theory [L. Bilot, A. Kawski, Z. Naturforsch. 17a (1962) 621], for the known dipole moment in the ground state mu(g) = 5.92 D, and alpha/a(3) = 0.5 (alpha is the polarizability and a is the Onsager interaction radius of the solute) yields for ABN: (1) the empirical Onsager interaction radius a = 3.3 angstrom, (2) the dipole moment in the excited S-1 state mu(e) = 7.14 D which agrees very well with the value of mu(e) = 7.20 D obtained by Borst et al. [D.R. Borst, T.M. Korter, D.W. Pratt, Chem. Phys. Lett. 350 (2001) 485] from Stark effect studies. Both values of Pe concern free ABN molecule and differ significantly from the values of mu g (8.0 D, 8.5 D and 8.3 D in cyclohexane, benzene and 1,4-dioxane, respectively) obtained by Schuddeboom et al. [W. Schuddeboom, S.A. Jonker, J.M. Warman, U. Leinhos, W. Kuhnle, K.A. Zachariasse, J. Phys. Chem. 96 (1992) 10809] from the time-resolved microwave conductivity measurements which are solvent-dependent. The group moment additivity law in the case of ABN molecule is approximately applicable, both in the ground and in the excited electronic state. (c) 2006 Elsevier B.V. All rights reserved.