NANO METRIC ZNO CLUSTERS CONFINED IN HZSM-5 WERE PREPARED WITH DIFFERENT ZNO LOADINGS AND CHARACTERIZED BY X-RAY DIFFRACTION (XRD) AND TEM. THE PHOTO CATALYTIC DEGRADATION OF 4-NITROPHENOL IN AQUEOUS SOLUTION WAS CARRIED OUT BY USING SUPPORTED ZNO ON HZSM-5 UNDER UV LIGHT .THE INFLUENCE OF VARIOUS PARAMETER SUCH AS ZNO LOADING AMOUNTS IN CATALYST AND PH ON DEGRADATION WAS OPTIMIZED. THE EXPERIMENTAL RESULTS DEMONSTRATED THAT THE PRESENCE OF ZEOLITE IN ZNO/HZSM-5 CATALYSTS COULD ENHANCE ADSORPTION AS WELL AS DEGRADATION OF 4-NITROPHENOL. IT IS SUGGESTED THAT ENCAPSULATING THE SEMICONDUCTOR CLUSTER IN THE POROUS SUPPORT IS A POSSIBLE WAY TO INHIBIT OR TO RETARD THE ELECTRON-HOLE RECOMBINATION. THE HIGHER ACTIVITY OF ZNO /HZSM-5 IS MAINLY DUE TO FINE DISPERSION OF ZNO AND HYDROPHOBICITY OF SUPPORT.