Electron device modelling at very high frequencies needs, as a preliminary step, the identification of suitable parasitic elements mainly describing the passive structure used for accessing the intrinsic device. However, when dealing with device modelling at millimetre-wave frequencies conventional lumped parasitic networks necessarily become less adequate in describing inherently distributed parasitic phenomena. In this paper, a distributed approach is adopted for the modelling of the parasitic network and a new identification procedure, based on electromagnetic simulation and conventional S-parameter measurements, is proposed. The intrinsic device, obtained after de-embedding from the distributed parasitic network, is particularly suitable for the extraction of accurate nonlinear models. Preliminary validation results are provided in the paper.