Strontium iron oxyhalide perovskitic oxides were investigated by electrochemical characterization as bi-functional electrocatalysts for oxygen evolution (OE) and oxygen reduction (OR) reactions in alkaline media. The electrochemical investigations showed that the presence of lower levels of oxygen and higher levels of chloride, as in Sr 4 Fe3O 8 Cl 2 and Sr 2 FeO 2 Cl 2 significantly enhanced the oxygen evolution and reduction over the other perovskitic oxides. Additionally, Sr 4 Fe3O 8 Cl 2 and Sr 2 FeO 2 Cl 2 was proven to have high bi-functional activity due to an overpotential gap ( E = 0.70 V) between the OER and ORR much lower than that of other similar perovskite bi-functional catalysts. In comparison with other strontium iron oxyhalide based electrocatalysts, Sr 2 FeO 2 Cl 2 was shown to have higher OER activities among all investigated catalysts. This work demonstrates that the oxygen-deficient layered perovskites of the type A 2 BO 2 X 2 are a new class of high-performance electrocatalysts for oxygen evolution (OE) and oxygen reduction (OR) reactions in alkaline media.There is a growing interest in catalysis research on non-precious metal catalysts that perform well enough to replace the precious and rare metal based catalysts. 1-3 The concept of a regenerative energy cell becomes attractive for energy conversion and production. In this system H 2 is consumed in a fuel cell and in turn water is split to produce O 2 and H 2 . Therefore, bifunctional catalysts that can serve as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are necessary for these regenerative energy systems. Considerable research and development has been directed toward developing robust materials for the OER and ORR, 4 that is, appropriate materials for the demanding reactions such as rechargeable metal-air batteries, 5,6 fuel cells, 7,8 water splitting, 9,10 electrolysis, 11 and solar synthetic reactors. 12 OER is an efficiency-limited process involving a four-step oxidation of water to molecular oxygen and has been widely used as an anodic reaction in electrolysis cells. 13,14 However, ORR also supports four electron reduction of oxygen and has been utilized for cathodic reactions in fuel cells. [15][16][17] The well-known catalysts for OER are based on the ruthenium or iridium oxides 18-22 whereas their activity in ORR is very moderate. 23 On the other hand, platinum-based materials have been most suitable for ORR 12,24-26 but are less active for the reverse reaction, OER. 27,28 Current developing methodologies are focused on creating precious metals and their alloy-based oxides, which were found to behave as the best bifunctional catalysts, but the scarce resources and high cost of these metals limits their long-term practical applications. 29-31 Therefore, it is important to focus on finding new types of material for water electrolysis that are comprised only of earth-abundant elements.Perovskites and layered perovskites, Ruddlesden-Popper phases, are of great interest for developing noble metal-free alternativ...