The present invention relates to the redox buffer electro-catalyst for bi-functional air electrode of metal-air batteries and fuel cells, wherein an electro-catalyst comprising of redox buffer oxides facilitates bi-functional activity of air electrode towards oxygen reduction and oxygen evolution reactions at the air electrode-electrolyte interface. The bi-functional activity of electro-catalyst comprising of redox buffer oxides is superior, due to improved electron transfer ability in comparison to electro-catalyst without redox buffer oxides.