NO-contg. air was purified by NH3 treatment in a catalytic reactor at 150-400 degrees C. Zeolite was catalyst deposited by in situ method on the FeCrAl foam surface (30 pores on in.). The concns. of NOx and NH3 in the inlet and outlet streams were measured by using Fourier transform IR spectrometer and the conversion of the reactants and reaction selectivity to N-2 were detd. The tests showed a high catalytic activity (up to 78%) and selectivity (about 95% below 300 degrees C). Above the temp., the oxidn. of NH3 began to dominate. Addnl., the measurements of the flow resistance through the catalyst bed for varying air flow rates were made and compared with the calcd. values of flow resistance through the granular and monolith types of beds, resp.