To understand more fully the factors that contribute to the formation and mass transfer of products within a burning cigarette, and to specify the type of reactions occurring, it is necessary to know the velocity of gases inside the combustion coal. In this study, velocities have been calculated from pressure and temperature distributions inside the burning cigarette. Gas velocities as high as 400 cm s−1 occur within the coal during a puff. Thus the residence times of gases in the coal can be much lower than 1 ms. This time is not long enough to allow molecular reactions of primary products in the gas phase to contribute to the final products.