A number of radioactivity management features exist in the current generation Indian PHWRs that helps in reducing radioactivity concentration within the containment during normal as well as under accident conditions. These systems employ charcoal filters for the removal of airborne organic iodides in containments. These filters would be exposed to different flow rates, iodine concentration; during operation leading to higher temperatures. The temperature transients in these filters during filtration process are important from safety point view. For safety assessment, a numerical model based on finite difference was developed that can predict the temperature variations in charcoal bed under various operating conditions. Parametric studies have been conducted w.r.t flow rate and iodine concentration. The details of numerical model and the studies carried out are presented in this paper.