The implementation of a charging infrastructure network is the necessary prerequisite for the diffusion of Electric Vehicles (EVs). In this paper a methodology to calculate the required number of charging stations for EVs and to set their position in a road network is proposed. The aim is to planning the distribution of services area to host charging infrastructures. Using the demand (the flow of EVs) and the supply (the road network where they will be positioned) through a two-level model were the locations initially identified (first level) and thereafter the number of charging stations for each service area (second level) evaluated. The paper deals with the intersection of three main topics: the vehicle technologies (engine and battery pack specifications), the charging station characteristics and the EVs flow. After verifying the model and the solution procedure on a test road network, the methodology is applied in a high dimension case, considering the Italian highway network.