A porous CaZrO3/MgO composite with similar to1% nanodispersed platinum was synthesized in air using several in situ reactions, including the pyrolysis of PtO2. The composite had a uniformly open, three-dimensional pore structure (porosity of 56%), with a narrow pore-size distribution. Catalytic NO decomposition to N-2 and O-2 and NO reduction by C(2)H4 were investigated up to 900 degreesC. In the absence of oxygen, the NO conversion rate reached similar to 52% for the direct decomposition and similar to 100% for the reduction by C2H4. The results suggested the possibility of the porous composite as a multifunctional filter for simultaneous filtering of hot gas and removal of NOx.