A combined exhaust gas aftertreatment system, consisting of a diesel oxidation catalyst (DOC), an NOx storage and reduction catalyst (NSRC, which also is called lean NOx trap, LNT), and a catalyst for selective catalytic reduction of NOx by NH3 (NH3-SCR) is studied experimentally. The catalyst samples are placed in series in an almost isothermal laboratory minireactor. Dynamic behavior of the system is examined under periodic lean/rich operation in temperature range of 200-400 degrees C with varying composition of the rich mixture, containing CO, H-2 and C3H6. Concentrations of gas components are measured at the inlet, outlet, and between the individual catalysts. The individual DOC, NSRC, SCR, NSRC-SCR, and DOC-NSRC subsystems are also examined. The DOC is used as the first element in the exhaust aftertreatment line. It is responsible for the oxidation of CO and unburned hydrocarbons (HC), and it also supports the oxidation of NO to NO2. NSRC and SCR converters are employed for the abatement of nitrogen oxides. A significant amount of NH3 can be formed in the NSRC as a byproduct of the NOx reduction, depending on the regeneration phase length, temperature, and gas composition. The generated ammonia is adsorbed in the SCR and used for additional NOx reduction. The dynamics of the combined system is investigated, and the conversions, selectivities, and reaction mechanisms in each converter, as well as mutual synergic and competitive effects, are discussed.