In recent years, the permissible limits of engine exhaust emissions are reduced considerably. Hence a quick warm-up and high conversion efficiency of the catalyst system is essential to meet upcoming stringent emission regulations. In the present work, the transient thermal behavior of an oxidation catalyst is studied using a one-dimension mathematical modeling approach with the focus on CO oxidation for dual-fuel engine application. At first, the heat generation due to chemical reactions is considered negligible for studying the warm-up behavior. Upon obtaining a good agreement between predicted warm-up temperature profiles with available literature data, the effect of an electrical heater on the warm-up behavior is investigated. The model is then extended by incorporating heat generation due to CO oxidation. A simplified reaction rate model is considered in order to reduce the computational complexity. It is observed that the simplified model agrees well with the experimental data for both low and high levels of CO concentration at the inlet, typical in dual-fuel technology when an engine is operated under diesel and dual-fuel modes, respectively. © 2019 Walter de Gruyter GmbH, Berlin/Boston.