We have investigated the impact of thermally evaporated hafnium oxide (HfO2) films on germanium substrates. Surface roughness of the HfO2 film was studied by scanning electron microscopy. Presence of crystalline GeO2 was evident from XRD results on as deposited films. Capacitance-voltage (C-V) and current-voltage (I-V) measurements of the as deposited MOS capacitors demonstrated a hysteresis of 2.3V and leakage current density of 10Amp/cm2 at IV respectively. Annealing of these films at two different temperatures of 500°C and 550°C in N2 ambience reduced the hysteresis to 0.9V and the leakage current density by five orders of magnitude. Observed increment of EOT after annealing indicates further growth of interfacial layer. Interface state density, estimated using conductance method after 550°C annealing, was 5.1×1012 cm -2eV-1.