In the first section of this project, a sensitive elecrocatalyst is made in order to determine the concentration of H 2 O 2 in synthetic and real samples. In this nanocatalyst the electrochemical behaviour of H 2 O 2 on glassy carbon electrode modified by copper nanoparticles deposited on functionalized carbon nanotubes (f-CNT/Cu Np) using cyclic voltammetry has been studied. The results were shown that copper nanoparticles as a heterogeneous catalyst had catalytic effect on the reduction of H 2 O 2 on the surface of a modified glassy carbon electrode. XPS, TEM, EDX analysis were performed on f-MWCNT/deposited of Cu Np to show successfully functionalization of MWCNT and formation of Cu nanoparticles. In the next section the photocatalytic degradation of Acid orange (??) (AO) was examined using the nanophotocatalyst of Cu (II)/TiO 2 /Al-MCM-41 under UV and visible light irradiation. The nanosized TiO 2 immobilized on mesosphere Al-MCM-41 was prepared by sol-gel method. Band gap of TiO 2 was modified by doping TiO 2 with Cu (II) using the impregnation methods with Cu (NO 3 ) 2 .7H 2 O as precursor. The structure of nanocatalyst (Cu(II)-TiO 2 /Al-MCM-41) was characterized by several analytical techniques including X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDX), UV-visible adsorption spectroscopy and BET surface area. The result show that Cu(??) doping induced the enhancement of photocatalytic degradation and optimal Cu(??) doping was 25%. Operational factors influencing the photocatalytic activity of nanocatalyst such as solution pH, photocatalyst dosage, dopant content and initial dye concentration were studied and optimum values were attained as: 0.15 g of photocatalyst, 25 ppm for AO(??), pH of 6.8.