To reduce the harmful pollutants in cold start emissions, this study has been considering microwave dielectric technique for rapid catalyst heating. A dielectric material, having a relatively large loss factor at 2.45GHz was selected. This was coated to the exhaust catalyst allowing microwave energy to be deposited efficiently. The developed system has been tested successfully using a single-mode cavity in conjunction with a model gas. Moreover, a concept for practical in-vehicle system using the microwave heated catalyst has been proposed.