Hydroxyl groups on the surface of Li2O were studied by using a diffuse reflectance method with Fourier transform infrared spectroscopy at high temperature up to 833K under controlled D2O or D2 partial pressure. Multiple peaks due to the stretching vibration of 0-D were observed at 2748, 2717, 2660, 2620, 2540, 2520, 2490cm−1 showing a different behavior with temperature or atmosphere. When D2 was added to the sweep gas, peak intensity of 2660 and 2620cm−1 decreased. This result indicates that the surface nature is influenced by oxygen potential. Assignment of observed peaks to the surface nature was also discussed.