Loop heat pipes (LHP) are controllable heat transfer devices that may operate in different regimes. When there is a possibility of redistribution of liquid between the evaporator and condenser, the regime of autoregulation is realized. Such a regime produces a performance characteristic of a specific form and makes it possible to implement control over an LHP temperature within a certain range of variation of heat load by means of corresponding selection of the constructive parameters. Active control is more reliable and precise. It is realized by means of thermal action on the returning flow of a working liquid. It was shown in the experiments that active control provides practically constant temperature within the control range.