Abstract: A mixed metal oxide powder of nominal composition M.sub.x M'.sub.x ' . . . , O.sub.z, wherein M, M', . . . are metal elements and each of x, x', . . . z is greater than zero, is produced by forming an aqueous solution comprising metal salts such that the solution contains at least some of the metal elements of the mixed metal oxide in a desired ratio and comprises at least one oxidizing agent such as a nitrate of one of the metals, and at least one reducing agent such as an organic acid. The oxidizing and the reducing agent as well as the ratio of the former to the latter are chosen such that the thus-formed tuned solution undergoes an exothermic reaction occurs at a desired rate and at a desired small temperature range. Aerosol-droplets of essentially equal dimensions are generated from the tuned solution and are sprayed into a heated gas jet.