We intend to perform an inelastic neutron scattering experiment on para-H2 adsorbed in L-Isoleucyl-L-valine (IV) microporous systems using the TOSCA spectrometer. IV is one of a class of materials (dipeptides) showing interesting properties (selective adsorption of gases and of solutes in water, active transport properties through the pores) that cannot be readily explained in terms of pore size only. INS can study the dynamical nature of the phenomenon with regard to the interaction of H2 molecules with the pore walls.