Hydrogen production as a clean energy carrier through catalytic hydrolysis of sodium borohydride has attracted widespread attention. This research addresses the synthesis of a cobalt nanocatalyst stabilized on graphitic carbon nitride (Co/g-C₃N₄) via chemical reduction and evaluates its performance in hydrogen production. Characterization of the nanocatalyst was performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). XPS results confirmed the formation of Co-B and Co₃O₄ phases on the polymeric substrate, and electron microscopy images showed uniform distribution of cobalt nanoparticles below 50 nm in size without aggregation. Investigation of catalytic activity in hydrogen production was conducted using a volumetric measurement system, with results indicating 100% hydrogen production efficiency under optimal conditions including 50 mg catalyst and 10 wt% sodium borohydride concentration. The use of graphitic carbon nitride substrate increased hydrogen production rate by twofold compared to the catalyst without stabilizer. Kinetic studies revealed a partial first order with respect to the catalyst and partial order less than one with respect to sodium borohydride. The activation energy was calculated as 37.94 kJ mol⁻¹, activation enthalpy as 35.53 kJ mol⁻¹, and activation entropy as –186.7 J mol⁻¹ K⁻¹. The proposed mechanism is based on simultaneous adsorption of borohydride ions and water molecules on the catalyst’s active sites. This study represents an effective step toward developing non-precious and low-cost catalysts for green hydrogen production.