The experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 kg/m2 s and the base heat flux varied from 30 to 80 kW/m2. Water enters the test channel under subcooled conditions. The samples are silicon oxide (SiOx), titanium (Ti), diamond-like carbon (DLC), and carbon-doped silicon oxide (SiOC) surfaces with static contact angles of 26 deg, 49 deg, 63 deg, and 104 deg, respectively. The results show significant impacts of surface wettability on heat transfer coefficient.