The aim of this thesis is to design a thermal analysis workflow for design of nano and micro satellites at the Space Center EPFL. Currently orbiting Swiss Cube nano satellite and a future extrasolar planet observation mission CHEOPS were selected as cases of interest. Both projects are being implemented and managed by the Space Center EPFL. We use mechanical models and environmental constraints for the above satellites to setup a Finite Elements Modeling software environment (Abaqus by Dassault Systems) to calculate temperatures as a function of satellite position in orbit. Thermal modeling was validated using analytical model and actual data from the Swiss Cube nano satellite. We have obtained good results and identified subsystems which have to be modeled in high detail (PCB material properties and battery behavior). Results obtained for CHEOPS design and selected orbit shows an asymptotic tendency of temperatures everywhere in the model that may be very useful from a thermal control point of view due to the high accuracy needed at the CCDs of the telescope, CHEOPS’ payload. Thermal design workflow will be used in future projects of the Space Center EPFL.