A new method for the estimation of properties of pure organic compounds is presented. Estimation is performed at three levels. The primary level uses contributions from simple groups that allow describing a wide variety of organic compounds, while the higher levels involve polyfunctional and structural groups that provide more information about molecular fragments whose description through first-order groups is not possible. The presented method allows estimations of the following properties: normal boiling point, critical temperature, critical pressure, critical volume, standard enthalpy of formation, standard enthalpy of vaporization, standard Gibbs energy, normal melting point and standard enthalpy of fusion. The group-contribution tables have been developed from regression using a data set of more than 2000 compounds ranging from C = 3-60, including large and complex polycyclic compounds. Compared to the currently used group-contribution methods, the new method makes significant improvements both in accuracy and applicability.