In a tokamak discharge, the external fuel, the hydrogen desorbed from the wall and a fraction of the plasma flux which recycles from the limiter enter the discharge as wall-temperature hydrogen molecules. In tokamak transport codes, the neutral hydrogen is usually introduced at the plasma edge as atoms with an energy of several eV. Recently the importance of molecular effects has been emphasized in Monte-Carlo neutral transport modeling of divertor chambers [I]. In this paper, we