We report the structural and electrical properties of ion beam sputtered ZnO films vacuum annealed at varying temperatures. XRD results revealed that the films grow along the c-axis. The crystallite sizes increase from ~8 to ~30 nm upon annealing at 800 ºC. Annealing aided to recover the compressive strain and regain the standard lattice parameter values. The RMS surface roughness increased to ~5.0 nm after annealing at 800 ºC as observed in AFM micrographs. Increased resistivity on the annealed films suggested that the oxygen vacancies are compensated by de-trapped oxygen at grain boundaries.