The purpose of the M.Sc. thesis was to design a supporting structure for an electric tricycle. The main objective was to build a concept of the structure with the lowest possible mass. However, its size, functionality and load-carrying capacity need to be comparable to the existing solutions on the market. In the introductory part, different types of supporting structures, shapes of profiles and materials are discussed and analysed in order to select the most mass-efficient solutions. We came to the conclusion that a steel spaceframe chassis is the most optimal option. In the next phase, various linear models of the chassis were built, on which the anticipated loads were applied. An analysis of strength and stiffness was then carried out, which helped us to determine the best solution. The chassis was designed in detail in a 3D modelling program and the strength and stiffness control were performed once again. To confirm the suitability of the structure, deflections and the fatigue of welded beams were analysed. In the last phase, the necessary technical documentation was drafted.