The female part (F) receiving the male part (M) comprises internally a tubular guide (4) with which the male part cooperates in a tight sealing manner (joint 20); the male and female parts respectively comprise at the input thereof a pivoting insulation flap (19; 17) which can open in a sequence when the male part penetrates the female part prior to the opening of the flap valves (15; 9) of the portions of the fluid circuit (13,7). The invention can be used to fill tanks of automobiles with cryogenic fluid, particularly liquid hydrogen.