In by-product coke oven battery, pulverized coal blend cake is carbonized in a series of coking chambers. Each cake of coal blend is contained between two heating walls in which number of inverted U-shaped flue ducts are embedded. Heat generated due to combustion of gaseous fuel in the flue duct is utilized for carbonization of coal. As the direction of flue gas changes periodically after every 30 min, and the twin coal beds on either side of heating wall are at 10 h heating lag, thermal dynamics set in the gas and walls. Numerical study of process transients reveals that positional gas temperature in the flue duct oscillates with flow reversal. The maximum and minimum temperatures show a rising trend with flow reversal during coking cycle. The temperature at the inner walls and outer walls of the flue duct show periodic rise and fall with the flow reversal, and show drastic drop at the time coke is pushed out. Similar characteristics are observed for wall surfaces facing coke bed, but local oscillation is almost damped out.