The choice of catalysts is the question of utmost importance when creating a catalytic conversion system. The
main parameters needed when choosing a catalyst include clear definition of the composition, temperature and
flow rate of the exhaust gas, which, in turn, are determined by design choices, engine operation mode, fuel and
air supply systems of the engine. The following subsections present the results of studies and analysis of the
most efficient catalytic coatings for use in a complex catalytic conversion system of a gas engine. Three-way
catalyst was experimentally tested on motor test bench. Selective catalytic reduction system was investigated by
computer simulation technique.