The results of experimental study and mathematical modeling of a fuel processor for the production of pure hydrogen from diesel fuel with a productivity of 600–700 g (H2)/h, consisting of an adiabatic reactor for diesel fuel pre-reforming followed by steam conversion of pre-reforming products in a catalytic Pd–Ag membrane reactor for hydrogen extraction are presented. The membrane reactor consists of 32 membrane modules arranged in 8 sections of 4 modules each. A mathematical model has been developed and two schemes of layout of the modules in the membrane reactor have been simulated. One scheme involves the cross-flow distribution of flue gas and fuel gas reformate to individual modules and leads to overheating of the input modules and cooling of the output modules. The other scheme with the cocurrent distribution of streams, along both the reactant path and the flue gas path, is preferable from the viewpoint of the temperature uniformity of different modules within a section. On the basis of the data obtained, an estimated calculation of the parameters of a power generation unit with a battery of low-temperature fuel cells has been made. For the example considered, the thermal efficiency of the fuel processor is 87%. With an efficiency of the fuel cell battery of 42%, the electrical efficiency of the fuel cell power unit will be 36%.