The conversion process is performed by means of catalyst which accelerates the chemical reactions. It remains unchanged through the process and able to sustain high temperatures caused by incoming exhaust stream. Most frequently, precious metals such as Platinum (Pt), Palladium (Pd), Rhodium (Rh) and Vanadium (V) are being used as catalysts and because of their rareness and outstanding ability, catalytic converters become among the most expensive devices in a vehicle. Though the researchers begin to replace them with oxides of base metals, which are much cheaper, such as Zinc (Zn), Aluminum (Al) and Magnesium (Mg), however, due to their lower performance compared to the precious ones, they do not have any other choice rather than to keep on implementing those expensive metals for automotive catalysts and other industrial applications.The experiment is carried out to analyze the performance characteristics and behavior of the three-way ceramic monolith catalytic converter (TWCC) especially its efficiency in reducing the amount of pollutants. Experiment is conducted to compare the performance of two ceramic converters of different hydraulic diameter, channel length and cell density on conversion efficiencies and pressure drop. By observing the results, suggestions on the considerable design geometries for catalytic converter properties are made.Emission test on engine test bed with converter installed and how engine operating conditions would influence the performance of catalytic converter is investigated. The test is done at various engine speeds and at different air-to-fuel ratio.The content of carbon dioxide (CO2), carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NOx) and oxygen (O2) are measured before and after the converters using the MRU Delta 1600-L multi-gas analyzer which is used during the emission test.After completing the test, the converters were cut to extract the substrate or ‘honeycomb’ inside the housing and being analyzed for microstructure and materials composition using Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis (EDX).The main objective of the paper is to compare and analyse the performance characteristics of converters from PROTON Wira 1.3L and another one from FIAT Punto Selecta 1.2L. Both converters had same substrate material.To verify the results obtained from the experimental works, computer simulation of a catalytic converter system is designed