Silicon (Si) with dangling bonds that are fully passivated by hydrogen (H) is investigated using the well-known non-self-consistent perturbative pseudopotential method (PPM) of M. Jaros. The role of H atoms is studied from a different point of view compared with previous works: (i) the modifications due to these atoms are calculated according to the Si bulk states, (ii) the gap variations with the Si–H bond length, and (iii) the gap variations with the Si/H band line-ups are investigated. This work is an attempt to shed light qualitatively on the role of hydrogen in the electronic properties of porous silicon (PSi).