Remarkable enhancement of the electrical conductivity and electrocatalytic activity is demon-strated as a result of the transformation of crystal structure between Sr₂ Mn₂ O₆ and CaSrMn₂O₆. The structure of Sr₂ Mn₂O₆ is known to consist of dimeric units of face-sharing MnO₆ octahedra. Whereas, CaSrMn₂ O₆ contains individual octahedra, connected to each other through corner-sharing. Herein we show that the changes in the crystal structure result in significant improvement of the electrical conductivity, by five orders of magnitude, for CaSrMn₂O₆ compared to Sr₂ Mn₂ O₆. Variable temperature conductivity studies from 25–800°C indicate semiconducting properties for both compounds, where the enhanced conductivity of CaSrMn₂ O₆ persists in the entire temperature range. The electrocatalytic activity of both compounds toward oxygen evolution reaction (OER) has also been investigated, indicating superior OER activity of CaSrMn₂O₆ compared to Sr₂ Mn₂ O₆ . A pronounced improvement in the onset potential and kinetics of OER is observed for CaSrMn₂ O₆ . These studies demonstrate an important correlation between crystal structure, electrical conductivity and electrocatalytic properties