Physicochemical properties of compounds are important determinants for their environmental fate and ecotoxic potential. A number of calculation methods can be used to estimate such molecular properties from an analysis of the chemical structure. In the class of group contribution methods, the property value is derived from individual contributions related to certain substructural units and structural features of the compounds. The software system SUBCON was developed to allow the implementation of a wide range of group contribution schemes in an efficient and convenient way.

After a short description of some main features of SUBCON we will present various implementations for the three molecular properties molar refraction, Henry's constant and octanol/ water partition coefficient. The comparative analysis of five different group contribution schemes for each property based on medium-size data sets with experimental values taken from literature reveals significant differences in the prediction performance. Furthermore, the performance of each calculation method is related to relevant structural features of the compounds to allow a more detailed evaluation. The results lead to recommendations of certain schemes as the current methods of choice.