In this study, metal/ZnO contacts were thermally annealed at different temperatures (as-dep., 400$^{circ}C$, 600$^{circ}C$, 800$^{circ}C$, 1000$^{circ}C$) for the investigation of electrical properties, and surface and interface characteristics. The analysis of the element composition and the chemical bonding state of the surface was made by the XPS(X-ray photoelectron spectroscopy). An attempt was made to establish the electrical property-microstructure relationship for the (Ti, Au)/ZnO. The Ti/ZnO contact exhibits an ohmic characteristics with a relatively high contact resistance of 4.74${ imes}$10$^$-1/ $Omega$$ extrm{cm}^2$ after an annealing at 400$^{circ}C$. The contact showed a schottky characteristics when the samples were annealed at higher temperature than 400$^{circ}C$. The transition from the ohmic to schottky characteristics was contributed from the formation of the oxide layers as was confirmed by the peaks for O-O and Ti-O bondings in XPS analysis. For the Au/ZnO contact the lowest contact resistance was obtained from the as-deposited sample. The resistance was slowly increased with annealing temperature up to 600$^{circ}C$. The ohmic characteristics were maintained eden fort 600$^{circ}C$ annealing. The XPS analysis showed that the Au-O intensity was dramatically decreased with temperature above 600$^{circ}C$.