[en] In the framework of generation IV development for nuclear reactors, actinide mixed oxides are considered for multirecycling plutonium fuels and for transmutation targets of minor actinides. In this context, new processes are being developed for either the synthesis of mixed uranium-plutonium oxide compounds for MOx fuel or uranium-americium target fabrications. The main purposes are to simplify and step up industrial processes as well as to decrease actinide dust dispersion, and liquid effluent and gaseous releases. Among options for conversion route, a novel and patented advanced thermal denitration in presence of organic additives was established successfully to synthesize UO_2+δ, U_0.55Pu_0.45O_2±δ, and U_0.9Am_0.1O_2-δ oxides. Here, we describe the different intermediate steps of this process together with the characterization of the oxides obtained. The data highlight several advantages of this new route for actinide conversion.