A synthetic route for advanced perovskites is elucidated that consists of a combined EDTA/citrate complexing of metal cations and the subsequent drying and firing at moderate temperatures. A fine-scale intermixing of cations is maintained during all the processing steps. The perovskite-type oxide is formed already in an intermediate step at 700°C by the reaction of an ultra-finely dispersed powder consisting of a mixed barium–strontium carbonate, a zinc–iron spinel, and zinc oxide. The process yields powders of good sinterability and finally dense ceramics composed of stoichiometric perovskite grains of the type (Ba,Sr)(Zn,Fe)O 3−δ.