The patterns of influence of gas molecules from the residual atmosphere in the vacuum chamber on the thermodynamic and gravimetric characteristics of porous absorbents of hydrogen are investigated by example of vanadium nitride (V, 10 at.% Ti)N$_{x}$ nanocrystalline thin films. As shown, the open pore structure of nanocrystalline thin films actively absorbs not only hydrogen molecules, but also larger molecules. Hydrogen saturation at 20°C leads to the fact that quite large part of the gas molecules from the residual atmosphere is blocked inside the pores. Thereby, the absorption capacity of the material is reduced (no more than 3 wt.%), and the temperature of hydrogen desorption is increased (500°C). High-temperature activation and hydrogen saturation at temperature of 250°C of nanoporous structure facilitate the reducing of desorption temperature to 275°C and the increasing of gravimetric capacitance to 7 wt.%.