In this paper an optimal operation mode control for a tramway with a hybrid energy storage system (battery+supercapacitor) is presented. The optimization process to obtain the setpoints for the control strategy is done by mean of multi-objective genetic algorithm (GA). The objective fitness functions are based on a cost model considering: the energy absorbed from the catenary, the battery+supercapacitor cycling cost and the cost of the lost energy in the crowbar. The aim of the proposed approach is to minimize the daily operating cost of the tramway taking into account the degradation of the energy storage systems and fulfilling the performance of the tramway in the catenary-less zone. Furthermore, a sizing analysis is done by comparing the proposed solution with a base scenario (supercapacitor based) to evaluate the impact on the daily operating cost under several unscheduled-stop events during the trip.