The internal rotation of 2,2'-bithiophene has been investigated in aqueous and acetonitrile solutions using three different solvation models: the discrete, the continuum self-consistent reaction-field and the combined discrete/self-consistent reaction-field, the polarizable continuum model being chosen for continuum calculations. Results indicate that the polarizable continuum model provides a satisfactory description of the solvent effects in acetonitrile solution. However, combined discrete/self-consistent reaction-field calculations are more appropriated in aqueous solution, where both the first-solvation shell effects and the polarization induced by the bulk solvent affect the rotational profile of 2,2-bithiophene. These results indicate that combined calculations are needed to model water soluble thiophene-derivatives. (c) 2005 Elsevier B.V. All rights reserved.