In this paper, the process of liquid evaporation is considered from the standpoint of the translational motion theory. It is assumed that the oscillation process in molecules of liquid as in crystals consists of fluctuations from equilibrium positions. In the liquid state, positions of the molecules vary with time, and in case of molecular- sized cavity near a molecule there can be an abrupt transition of the liquid molecule from one equilibrium position to another. An assumption has been made that liquid temperature increase during steady-state condition of molecules will result in decrease of steady-state duration time, jump frequency will be increased, and probability of molecule transition from free surface of liquid to the vapor space will also be increased. Hence, it is concluded that temperature increase will cause the increase of liquid evaporation rate. In accordance with the assumptions theoretical dependencies are elaborated for calculation of liquid evaporation rate on its free surface for a wide range of temperatures — from freezing point to boiling point. Also, the nature of temperature dependence of liquid evaporation rate on a solid heating surface during saturated bubble boiling is investigated.