Device and method for filling pressurized gas tanks, particularly vehicle pressurized hydrogen tanks, the device comprising a liquefied gas source, a transfer circuit comprising two parallel transfer lines each having an upstream end linked to the liquefied gas source, at least two separate downstream ends intended to be each removably connected to a tank to be filled, each of the two transfer lines comprising: a pump, a vaporizer for evaporating the pumped fluid, a branch for bypassing the vaporizer and a distribution valve(s) set configured to control the flow of fluid pumped and distributed between the vaporizer and the branch line, the device further comprising a storage buffer(s), which storage buffer(s) is(are) connected in parallel to each of the two transfer lines via a set of valves.