The development of catalysts is crucial to sustainable energy production. Water electrolysis can generate green hydrogen, which can be used to fuel cars and chemical plants. The slow kinetics of the oxygen evolution reaction (OER) in water electrolysis is the main challenge for more widespread applications. A higher overpotential—the additional energy needed beyond the equilibrium potential for the catalyst to operate efficiently—is required to overcome this kinetic barrier. Traditional catalysts use precious metals which are less sustainable and are unstable under high anodic potentials, making the development of catalysts based on earth-abundant metals important. High-entropy oxides, formed by combining five or more metal elements to achieve high configurational entropy, have robust crystal structures and high catalytic performance in thermochemical and electrochemical reactions. However, the high calcination temperatures often necessary for their synthesis can lead to particle aggregation which decreases the specific surface area. Therefore, the synthesis of high-entropy oxide nanoparticles with high specific surface area could allow them to have superior performance as electrocatalysts. This project involved the synthesis of these nanoparticles and an investigation of their catalytic performance and surface area. The nanoparticles were synthesized using a dicarboxylic acid-aided sol-gel method which facilitates the formation of nanoparticles such as perovskite oxides. The samples were characterized using X-Ray Diffraction, N2 Isotherm, Energy Dispersive X-Ray Spectroscopy, and Thermogravimetry-Differential Thermal Analysis. The catalytic activity of the synthesized catalysts for OER in alkaline water solutions was investigated using a potentiostat and a three-electrode electrochemical cell. The nanoparticles effectively catalyzed OER. This project contributes to the field of catalysts for sustainable energy conversion and storage. Future work may explore different metal combinations to further tune and optimize the catalytic properties of these materials.