In this project a one-dimensional model of three-way catalytic converter has been developed. This model includes energy and chemical species balance equations in gas and solid phases. Diffusion through solid phase has been taken into account by considering effectiveness factor. Surface oxidation and reduction reaction rates are Langmuir-Hinshelwood type rate expressions and chemical adsorption and desorption effects have been considered in rate expressions coefficients. After model verification, this model was used to investigate effects of input gas properties and geometric parameters on catalyst performance. Also heat and mass transfer coefficients effects on catalyst performance were investigated. Toward this purpose, transport coefficients have been increased between 1 to 5 times of their values in laminar flow condition. In practice this has been done by using protrusions in catalyst channel and decreasing critical Reynolds number and as consequence, making turbulent flow. Two functions have been defined to study effect of transport coefficients on catalyst light off and efficiency quantitatively. The light off related function and efficiency related function which had to be minimized. This study showed that, increasing these coefficients lead to reduction of light off time but their effect on steady state conversion efficiency is a function of engine’s operating conditions. Increasing these coefficients to more than 5 times of laminar flow condition has insignificant effect on light off time and increasing them to 2.23 up to 3 times of laminar flow condition results in maximum increase in efficiency during different operating conditions of engine. So increasing transport coefficients by making turbulent flow has optimum range in which minimum light off time and maximum increase in efficiency is achievable.