This study explores the catalytic oxidation of phenol using an iron-supported natural illite clay catalyst, focusing on optimizing operational parameters to enhance degradation efficiency while minimizing environmental impact. The effects of pH, temperature, catalyst dosage, initial phenol concentration, and H₂O₂ concentration were systematically examined. Optimal conditions were found at pH 3 and 50°C, which promoted hydroxyl radical formation and improved reaction kinetics. Under these conditions, the catalyst achieved a 99% phenol degradation rate and an 83% reduction in chemical oxygen demand (COD), with no detectable metal leaching, ensuring catalyst stability. The catalyst's characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), BET surface area analysis, and laser granulometry, confirming its structural integrity and stability. Additionally, the H₂O₂ concentration was optimized at 8.7 mM to enhance the oxidation process while minimizing reagent excess. An analysis of intermediate by-products revealed stepwise degradation, highlighting efficient oxidation pathways. Environmental impact assessments demonstrated that the catalyst, with its low metal leaching and high stability, had minimal toxicity to aquatic life, particularly fish, confirming its safe use in wastewater treatment applications. This study underscores the potential of iron-impregnated natural clays as stable, non-leaching, cost-effective catalysts for the treatment of phenolic pollutants, with reduced environmental risks.