Conformational analysis of 2,2'-dinitrobiphenyl (DNBP) performed at the B3LYP/6-31G level of theory has shown that the most stable form in vacuo is the conformer with the torsional angle of psi = 81.6 degrees. The theoretical simulations and the experimental dipole moments measurements have revealed that the molecular geometry of DNBP is distinctly modified by the medium. The torsional angle psi gradually decreases with increasing dielectric permittivity of the solvent. (c) 2005 Elsevier B.V. All rights reserved.