Tetrazoles and sulfoxide compounds have a wide range of applications in industries and are of great expectation to be environmentally friendly and cost-effective. This paper reports the introduction of zir- conium supported on Fe 3 O 4 nanoparticles through creatinine post-functionalization modification of Fe 3 O 4 (Fe 3 O 4 @Creatinine@Zr). The Fe 3 O 4 @Creatinine@Zr was characterized by a vibrating sample magnetome- ter, X-ray powder diffractometry, Fourier transforms infrared, scanning electron microscope, energy dis- persive X-Ray analysis, thermogravimetric analysis, and inductively coupled plasma. Fourier transform- infrared spectroscopy results confirmed that creatinine was successfully immobilized on the surface of Fe 3 O 4 –Cl with the presence of ν(C = N), and ν(C = O) bands of creatinine. X-ray diffraction data confirmed that the crystalline phase of Fe 3 O 4 was not destroyed after modification. Vibrating sample magnetometer analysis showed that the saturation magnetization of the Fe 3 O 4 @Creatinine@Zr was 28.6 emu/g. The SEM-EDX results revealed that the zirconium complex was successfully incorporated into the structure of Fe 3 O 4 .This catalyst displayed high catalytic performance in the synthesis of 5-substituted 1 H -tetrazoles and the selective oxidation of sulfides with classical and ultrasonic methods. The catalyst conferred strong Lewis’s acidity sites for the activity and selectivity of the reactions. The obtained results showed that the fast oxidation of sulfides was happened by 0.2 mmol g −1 of zirconium that immobi- lized on the Fe 3 O 4 nanoparticle at optimum condition (Sulfide (1 mmol), H 2 O 2 (0.6 mL), ethanol (3 mL) and catalyst (Fe 3 O 4 @Creatinine@Zr, 60 mg) at room temperature.) The results showed that ultrasonic was an appropriate method for the oxidation of sulfides to the related sulfoxide at the optimum condition. The 5-substituted 1H-tetrazoles were afforded at optimum condition (Nitrile (1 mmol), NaN 3 (1.2 mmol), H 2 O (3 mL), catalyst (100 mg) at 90 °C). The catalyst was separated by simple recovery and reused for seven periods without any remarkable decrease in the catalysis activity and selectivity. The output of this research can open a window for the synthesis the other organic materials under mild condition. ©2021 Elsevier B.V. All rights reserved.