A morphology-controlled ion exchange route has been investigated for the preparation of Copper Nitroprusside (CNP) nanosheet. Polyvinylpyrrolidone (PVP) was used as capping agent. The effect of PVP concentration during synthesis was also studied which provides a local control over the morphology of CNP nanosheet to produce an ultrathin CNP nanosheet. Effect of PVP concentration in crystal growth and mechanism has been established. Cyclic voltammogram shows that oxygen evolution reaction (OER) onset potential for CNP nanosheet was found to be 1.45 V with a measured current density of 26 mA/cm(2). Linear sweep Voltammetry test has also been conducted to analyze the electrocatalytic OER performance. Anodic slope of Tafel plot establishes higher OER performance of CNP nanosheet than commercial RuO2. CNP nanosheets was found to be cheap and efficient eletrocatalyst for water splitting reaction. Voltammetric current density has also been expressed as a function of average thickness of nanosheets. (c) 2018 Elsevier Ltd. All rights reserved.