The contribution of ENEA together with Rina-CSM to the Eurofusion programme “WPMAT-Advanced Seels” deals with the development of innovative RAFM steels able to withstand the critical temperatures typical of the different operational environments foreseen for the blanket of the first DEMO reactor. The optimization of the chemical composition and the Thermo Mechanical Treatment for these materials should be done according to the blanket operating temperatures that are related to two possible working conditions: the WCLL-BB (Water Cooled Lead Lithium Breeding Blanket) or the H(D)CLL-BB (Helium (Dual) Cooled Lead Lithium Breeding Blanket). On the one hand the “water-cooling” option implies a minimum irradiation temperature for the blanket material in the range of 280–350 °C. On the other hand, the “helium-cooled” and the “dual-coolant” solutions imply an operating temperature for the blanket material in the range of 650 °C. Therefore in the first case the target is the improvement of the toughness of the martensitic alloys; whilst concerning the second scenario the target is the development of more creep resistant martensitic steels, suitable to tolerate such a high operating temperature. In both the cases the Tungsten content plays a key role, both in terms of solid solution hardening and influence on the DBTT. Two alloys aimed at fulfilling the specifications for the two DEMO operating conditions, both with increased Tungsten content respect to Eurofer, have been produced and characterized. The mechanical properties of these two alloys are hereby reported and discussed.