Mn 2? doped ZnO nanopowder was prepared by simple sonochemical method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, optical absorption (UV-Vis), photoluminescence (PL), Electron Paramagnetic Resonance (EPR), Fourier transform infrared (FT-IR) spectroscopy and magnetization have been used to characterize the sample. XRD study revealed that Mn 2? doped ZnO had wurtzite hexagonal structure. Composition analysis by EDX indicated the presence of small amounts of manganese. Crystal field (Dq) and interelectronic repulsion (B, C) parameters are evaluated from optical absorption. SpinHamiltonian and bonding parameters are evaluated from the EPR study. Optical and EPR confirms that the Mn 2? entered into ZnO lattice as distorted octahedral site symmetry. FT-IR spectrum exhibited vibrational bands of Zn-O bonds. PL spectrum shows the emission bands in UV and visible region. Magnetization loop was measured and clearly shows typical ferromagnetic saturation behavior. The results suggest oxygen vacancies, especially singly ionized oxygen vacancies, play a crucial role in mediating ferromagnetism in the Mn doped ZnO system.