Regenerative Braking Systems (RBS) provide an efficient method to assist railways and hybrid electric buses to achieve better fuel economy while lowering exhaust emissions. In this paper regenerative braking concepts have to be studied in order to find an optimal way to combine a regenerative braking with a conventional frictional braking system to achieve maximal energy recuperation .This paper describes the principle, design and working of regenerative braking systems. A typical regenerative braking pattern is investigated for evaluating the availability of braking energy recovery. The results indicates that in a vehicle with active regenerative braking control, a significant amount of braking energy can be recovered, and the brake system does not need much changing from the brake systems of conventional passenger cars.