In practical applications, monolithic catalytic converters are operated at non-isothermal conditions. In this case, the active metal distribution along the length of the converter may influence its performance. Indeed, better conversions can be achieved by controlling the distribution of the same quantity of active material. In this study, we used a one-dimensional catalyst model to predict the transient thermal and conversion characteristics of a dual monolithic catalytic converter with Platinum/Rhodium (Pt/Rh) catalysts. The optimal design of a longitudinal noble metal distribution of a fixed amount of catalyst is investigated to obtain the best performance of a dual monolithic catalytic converter. A micro-genetic algorithm with considering heat transfer, mass transfer, and chemical reactions in the monolith during the FTP-75 cycle was used. The optimal design for the optimal axial distribution of the catalyst was determined by solving multi-objective optimization problems to minimize both the CO cumulative emissions during the FTP-75 cycle, and the difference between the integral value of a catalyst distribution function over the monolith volume and total catalytic surface area over the total monolith volume. (c) 2008 Elsevier Ltd. All rights reserved.