For prediction of properties of pure compounds in homologous series a shortcut version of the authors' QS2PR technique is introduced. The structure-structure relationship between a target compound and three predictive compounds from its homologous series is described in the short version with the number of carbon atoms and one easily calculated noncollinear molecular descriptor. This correlation provides predictions of high precision for properties of members of the homologous series, if property data for interpolation are available. It can also be used for short-range extrapolation with precision similar to that of asymptotic relationships. The advantages of the proposed method over the existing methods are that with the structural correlation parameters it predicts all structure-dependent properties of the target and enables estimation of its missing properties even if properties for only three predictive compounds are available. The method can also use as a descriptor the normal boiling temperature. (c) 2006 American Institute of Chemical Engineers AlChE J, 53: 150-159, 2007.