NiO is metal oxide which has applications in solar cells, electrochemical capacitors, photocatalysis, organic LEDs etc. Doping with cation like Cu and Li is done in NiO to overcome its high resistivity [1-3]. Pure NiO is an insulator having band gap around 3.6-4 eV which gets converted into a p-type semiconductor by creating Ni +2 vacancies by doping with cations. The band gap also gets reduced by this process. Room temperature ferromagnetism has been observed in Mn doped NiO nanoparticles synthesized by hydrothermal methods. Transition metal (Mn) doped NiO are Dilute Magnetic Semiconductors (DMS) which are used in spintronics devices increasing the processing speed and integration densities. An interaction between the host sp and Mn d levels take place in these cases. Unusual Magneto transport and Magneto optical phenomena like Faraday Rotation, GMR and magnetic field induced metal insulator transitions occur in DMS .