Perovskite-type lanthanum strontium iron oxide (LSFO) films were synthesized on Si substrate with metalethylenediaminetetraacetic (metal-EDTA) complex. The starting material of the metal composition has been La:Sr:Fe=1:3:3, followed by atmospheric sintering at temperatures ranging from 550 °C to 950 °C. The process produced LaSr₃Fe₃O_9.9 owing to the design of the metal-EDTA complex, and also crystals with other LSFO structures. LSFO particles were also prepared on carbon paper by using spraying and roasting processes for use as the air electrode in a metal-air secondary battery. The addition of surfactant to the (La,Sr,Fe)-EDTA solution made it possible to prepare uniformly distributed LSFO particles sized approximately 100 nm on carbon paper. The catalytic effects of the different LSFO films on the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were investigated. Unique solution-based synthesis with compositional accuracy for metal-air secondary battery has been proposed.