The purpose of the thesis is to develop a compressible and thermal model for automotive dampers. The selected approach is a lumped parameter modelling which shortens preliminary design sizing process if compared to a time-consuming detailed CFD. Twin tube configuration is taken as reference: four main regions are identified such as rebound, compression and reserve chamber which are filled with damper medium while the fourth is constituted by gas chamber. Starting from the simplest formulation, the incompressible one, each model is analysed including progressively compressibility and thermal effects. In the lumped system analysis also damper main solid parts are modelled. Temperature influence on viscosity is accounted for in both local and wall-friction losses.