In the present work, a new catalytic system based on palladium(II)-tetrazole complex immobilized on silica-coated Fe3O4 (Fe3O4@SiO2) nanoparticles ([Fe3O4@SiO2-Tet-Pd(II)]) is introduced. In the first stage, the geometry optimization and calculations of structural and electronic properties of molecular system 5-phenyl-1H-tetrazole-Pd (II) complex have been carried out at UB3LYP/6-31G*/LANL2DZ level of theory. Then, the [Fe3O4@SiO2-Tet-Pd(II)] was prepared via immobilizing 5-phenyl-1H-tetrazole as a suitable ligand on the surface of Fe3O4@SiO2 as a support. The [Fe3O4@SiO2-Tet-Pd(II)] as a novel magnetically catalyst was characterized by XRD, FT-IR, FE-SEM, EDS, TG-DTA and VSM. This heterogeneous catalytic system demonstrated high activity in the reduction of 2,4-dinitrophenylhydrazine (2,4-DNPH), 4-nitrophenol (4-NP) and Cr(VI) in the present of NaBH4 as the reduction agent at room temperature and was reusable five times with no obvious decrease of catalytic activity.