SUMMARY Flow aspect and temperature depression of cavity bubbles on a NACA16-012 hydrofoil were experimentally investigated with liquid nitrogen in order to comprehend the degree of thermodynamic effects on cavitation. The aspect of cavitating flows showed that cavity bubbles occurred at the leading edge of the foil and gradually expanded to the trailing edge as the inlet cavitation number decreased step by step. The streamwise length of cavity bubbles didn't so oscillated if the cavity length on the hydrofoil is in the condition of partial cavitation. Furthermore cavity bubbles observed were consisted of lots of tiny bubbles, as so-called cloud, and looked much creamier than those in water. On the other hand, as the inlet cavitation number decreased, the temperature depression measured with miniature diode sensors mounted on the hydrofoil increased and the area of the temperature depression gradually expanded to the trailing edge. These results showed that the increase and area expansion of temperature depression qualitatively corresponded to those of cavity cloud. In addition, a consideration based on heat balance in phase change around a bubble was extended to cavity cloud and the discussion can be concluded that the temperature diffusivity in cavity cloud is strongly suppressed by tiny bubbles.