<p>The depletion of fossil fuel reserves and environmental consequences of their combustion have accelerated the search for sustainable energy solutions. Among various alternatives, electrochemical water splitting, particularly oxygen evolution reaction (OER) has gained significant attention because of its critical role in clean energy technologies. Spinel-based materials, when combined with graphitic carbon nitride (g-CN), exhibit promising catalytic properties for enhancing OER performance. In present research, nanocomposite of g-CN integrated with SnFe₂O₄ was fabricated by hydrothermal approach and evaluated for its OER activity. Several analytical methods were used to analyze the resultant materials thoroughly. The SnFe₂O₄/g-CN composite displays a mesoporous architecture with uniformly distributed nanoparticles on g-CN nanosheets, hence enhancing active surface area and electron mobility. Nitrogen adsorption-desorption analysis validated the mesoporosity, while electrochemical assessment showed notably less overpotential of 226 mV at 10&#xa0;mA cm^− 2 and decreased Tafel value of 38 mV dec^− 1. Particularly, composite displayed outstanding long-term stability under an alkaline environment. These exceptional properties result from the synergistic interaction between spinel and g-CN, facilitating efficient charge transfer and providing abundant catalytic sites. Present research not only introduces unique non-transition metal spinel-based catalyst but also establishes a viable way for designing earth-abundant electrocatalysts for scalable OER applications.</p>