Abstract: This invention presents a process for conversion of gaseous uranium hexafluoride to an oxide product of uranium by introducing to a reaction zone in the presence of an active flame maintained in the reaction zone a first gaseous reactant comprising a mixture of uranium hexafluoride and an oxygen-containing gas and a second gaseous reactant comprising a reducing gas and temporarily separating the first and second gaseous reactants with a shielding gas which temporarily prevents substantial mixing and reaction between these gaseous reactants. The first and second gaseous reactants ultimately react in a primary flame to give a particulate uranium dioxide rich composition and residual reducing gas. An oxygen-containing gas as a third gaseous reactant is introduced through multiple downstream inlets with the inlet closest to the primary flame being at a location in the reaction zone where the uranium hexafluoride conversion to the uranium dioxide rich composition is substantially complete.