In the present paper, the influence of manganese doping on the energy storage capability of Ba_0.8Sr_0.2TiO₃ thin films is presented. The stored and recoverable energies have been calculated from the material's Polarization-electric field loop and the energy storage efficiency and figure of merit (F.O.M.) were deduced. For the undoped material, the energy loss is important and the breakdown field is low. At a suitable dopant rate, this effect disappears and a recoverable energy density of 4.4 J/cm3 has been found for 1% of manganese doping. In this case, an efficiency of 93.6% and a F.O.M. of 3.82 J/cm3 have been obtained. Moreover, it has been shown that the permittivity of the BST thin films doped at 1% Mn is rather stable and varies less than 2% between -80°C and 60°C, and that the dielectric losses tanδ are temperature independent and smaller than 0.014.