A method based on the continuum solvation model of Miertus and Tomasi (S. Miertus and J. Tomasi, Chem., Phys., 65 (1982) 239), which can be used to calculate the free energy change in transferring a molecule from the gas phase to a solvent, is presented. The solute is represented as a set of interlocking spheres with a polarisable point charge at each center. In order to reduce the number of atom types in the method, the atoms are assigned to classes based on the concept of molecular orbital valency state as proposed by Clementi. Solute polarisation by the solvent field and the effects of cavitation are included. The parameterisation, based on the Frage potential, and the results of the calculations for a series of molecules ranging from H 2 O to small peptides are presented. Other applications include ionic solvation and the formation of salt-bridges , which are essential for the stabilisation of amino acid residues with charged side chains. Initial results from the incorporation of this algorithm in a conformational study on Met-enkaphlin (met is methionine) are also presented.