Analysis of the inelastic neutron scattering (INS) spectrum of dihydrogen adsorbed at the cobalt site of a cobalt aluminophosphate (CoAlPO) catalyst shows that weakly bound dihydrogen is constrained to rotate with the molecular axis aligned with the electric field in the cavity and a more strongly bound species in a plane parallel to the surface. Hydrogen adsorbed on the Al3+ sites behaves as a slightly hindered three-dimensional rotor.