The emission regulations for internal combustion engines are becoming more and more stringent with the aim to reduce the pollutants emitted to the atmosphere. One of the most efficient means to meet upcoming stringent emission regulations is by reducing the pollutants emitted during the warm-up time and at low-load operating conditions by using an oxidation catalyst. In the present work, a 1-D mathematical model of an electrical heater assisted oxidation catalyst has been developed to study the effect of heater on CO conversion at low operating loads and during cold start conditions. The study has been conducted considering different power levels, heating durations (continuous and temporary) and heating volumes, and it promises to be helpful in tackling the problem. The results revealed that heater assistance to the oxidation catalyst improved the light-off performance, and temporary heating was found to be as effective as continuous heating in reducing the CO emission. Moreover, an indication parameter (light-off time reduction per unit power) has been developed, which can be used to optimize the power requirement of the heater.