Group contributions to the hydration free energy for a series of monosubstituted alkane (CH3-(CH2)(n)-X; n = 0-7) derivatives have been determined from Miertus-Scrocco-Tomasi (MST) continuum calculations. Particular attention is paid to the dependence of the group contributions on the procedure used to carry out the charge normalization in the MST model. The contributions of the functional groups (X) appear to be largely transferable along the homologous series of alkanes derivatives only when the local anisotropy of the solute's charge distribution is explicitly considered in the normalization of the solvent's apparent charges. (C) 2003 Elsevier B.V. All rights reserved.