Abstract <p>This study investigates the photocatalytic decolorization of Acid Yellow 36 dye using sintered ZnFe₂O₄ powder prepared at 500–900°C for 4 h. Photocatalytic experiments were conducted under artificial illumination using a Philips 250 W light source with an intensity of 1.48 × 10^–7 Ens s^–1. The decolorization process followed pseudo-first-order kinetics. Optimum conditions for decolorization were determined as an initial dye concentration of 50 mg/L, a ZnFe₂O₄ dose of 150 mg/100 mL, and an initial solution pH of 6.75. Under these conditions, a maximum dye removal efficiency of 88.18% was achieved within 100 min at 30°C. Increasing the reaction temperature enhanced the photocatalytic activity, with a positive enthalpy change (Δ<i>H</i>) of 20.55 kJ mol^–1 and a low activation energy of 22.61 kJ mol^–1. Additionally, the Fenton reaction using ZnFe₂O₄ nanopowder further enhanced the photodecolorization efficiency, demonstrating its potential as an effective photocatalyst for wastewater treatment.</p>