At presently, manganese oxide nanoparticles (MnO2 NPs) have intrigued material science researches XRD widely owing to its extensive variety of applications. In this study, the manganese oxide nanoparticles were prepared by using manganese chloride Tetra hydrates salts. The samples were characterized to find the structural, functional and magnetic properties by XRD, FT-IR, and VSM respectively. An attempt is made to summarize the complete field dependent magnetization study of the synthesized material is presented. Structural studies by XRD indicate that the synthesized material as tetragonal crystal structure. FT-IR analysis revealed stretching vibrations of metal ions in tetrahedral and octahedral co-ordination confirming the crystal structure. The Antiferro magnetic behaviour was observed at room temperature with no saturation magnetization and hysteresis in the region of measured field strength. These measurements as a function of temperature and field strength showed a reduction in Anferromagnetic temperature.