One of the problems of the hydrogen systems＇ operational use is the ensuring of these systems＇ internal safety at hydrogen venting to atmosphere since, during the above procedure, in a number of cases, there is a possibility of air penetration to the vent pipeline and then to the vapor space of system tank that leads to a fire-explosion risk situation and deterioration of product stored in the system. The one-parameter mathematical model has been developed to describe the mass transfer process, taking place at the nonstationary mode of gaseous hydrogen outflow to atmosphere in case of availability of counter air flow in the vent pipeline. The calculated dependency, allowing to estimate a safe level. for reduction of hydrogen venting velocity, has been obtained based on the mathematical model and experimental data for stationary mode of gaseous hydrogen outflow to atmosphere, The structure of the venting device, providing the safe operational use of hydrogen systems at venting of gaseous hydrogen to atmosphere, has been proposed.