SUMMARYWith the advancement of the manufacturing technologies to produce new generation analog=digital communication systems, immitance data modelling has gained renewed importance in the literature. Speciÿcally, models are utilized for behaviour characterization, simulation of physical devices or to design sub-systems with active and passive solid-state devices. Therefore, in this paper, new computer aided tools are presented to model one port immitance data by means of linear interpolation techniques. The basic philosophy of the new modelling tools is based on the numerical decomposition of the immitance data into its minimum and Foster parts. Computer algorithms are presented to model the minimum and the Foster parts of the given immitance data. Implementations of these algorithms are exhibited by means of examples. Depending on the application, modelling tools based on linear interpolation techniques may present 'computational and practical' advantages over the existing interpolation techniques, non-linear curve ÿttings or regression methods. It is expected that the new modelling tools will be utilized to provide initial circuit topologies to the commercially available analysis=simulation and design packages.