The specification describes a method of retrofitting a chemical plant which initially comprises a hydrotreating section and a steam reforming section, the method involving introducing a tail-gas treatment which is arranged to accept tail-gas from the steam reforming section and generate a crude H2 stream which is used at least in part to provide fuel for the fired reformer within the steam reforming section. The specification also describes an integrated hydrogen and hydrotreatment plant which incorporates a tail-gas treatment unit, and a process for producing hydrogen and carrying our hydrotreatment using the plant.