The steady state response of a monolith catalytic converter to changes in operating conditions and monolith design parameters has been examined on the basis of a mathematical model. The model considers both catalytic and gas phase homogeneous reactions of a hydrocarbon and allow for axial conduction of hear in the solid substrate. Higher inlet temperatures and concentrations, and lower gas velocities are shown to result in higher conversion efficiencies. Metallic monoliths, having higher channel density offer superior performance to ceramics, and channel size and shape had significant influence on conversion and temperature profiles along the monolith channel. A proper choice of catalyst distribution along the monolith axial dimension resulted in a solid temperature profile subjected to less thermal stress. The possible effect of changes in catalytic material on the overall converter performance has been also examined.