Abstract: A method for determining a tank pressure in a tank before the tank is filled with pressurised, gaseous hydrogen, according to which method an accumulator, in which the hydrogen to be used to fill the tank is stored as liquid hydrogen, is connected to the tank by means of a filling line and a subsequent check valve of the tank wherein hydrogen is pumped from the accumulator into the filling line by means of a pump and the filling-line pressure arising in the filling line during the pumping is measured, wherein the check valve is opened if the filling-line pressure exceeds the tank pressure, and wherein the tank pressure is determined as the filling-line pressure that exists when the check valve is opened.