The purpose of the present work is to numerically calculate cooling of thin deuterium jets to create units for receiving high-speed cryogenic monodisperse targets. The model of cryogenic jet outflow into the low pressure area has been created. Using PHOENICS software the temperature change of the surface and the interior of a jet over time for various external parameters has been investigated by the numerical method. The dependences of temperature changes of liquid deuterium jets have been obtained along the jet surface and along the radius depending on the jet diameter, velocity, initial jet temperature and pressure in the working chamber of units for receiving cryogenic monodisperse targets. The principal possibility of creating high-speed cryogenic monodisperse targets is shown. According to the calculations, at injection of thin liquid Deuterium jets with a speed of up to 100 ms‒1 into the working chamber with low pressure, the jets do not have time to freeze at a distance of up to 1 mm. The results of numerical calculations can be used to develop units for receiving high-speed cryogenic mono-disperse targets.