A technique for incorporating the convective transport of mass into two-dimensional photochemical atmospheric models was tested. The convective mass fluxes were calculated from the three-dimensional general circulation model CCM3 and used to assess the impact of convection on the gas composition of the upper troposphere and lower stratosphere. The technique was tested using two two-dimensional photochemical models for modeling atmospheric radon distribution. The numerical experiments indicated that the convective rise of mass has a profound impact on the distribution of gases with surface sources and short atmospheric lifetimes. Studying the role of convection in the budget of hydroxyl radicals, we find that the convective rise of mass can lead to an increase in the odd-hydrogen concentration to 50% at heights between 10 and 15 kin over the equator, which is consistent with measurement data. The relationship between convective processes and the chemical activity (as well as solubility) of gases involved in convection is shown to be important.