An Ultra High Vacuum Low Temperature Scanning Tunneling Microscope (UHV_LT_STM) for singe atom manipulation on Molecular Beam Epitaxy (MBE) grown nitride semiconductor samples has been designed and constructed. The operational capability of this STM is demonstrated on Ag(111) and GaN (000ī) surfaces at 6K and 80 K. On Ag(111) surface, individual silver atoms are repositioned by manipulating with the STM-tip. Conductance tunneling spectroscopy data acquired on this surface confirms the surface state onset at -63 meV. STM images of GaN (000ī) surface at 6 K shows novel low temperature reconstructed structures. STM images of this surface at 80 K reveals coexistence of 3x3, 6x4 and 6x6 regions and low temperature reconstructed structures.