Frontal radical polymerization of vinyl monomers in non-stationary mode is investigated theoretically. It is shown that the formation and the time of establishment of steady-state polymerization heat autowaves considerably depend on the initial temperature, T-i. When T-i is less than the adiabatic heating temperature (T-a), the excess heat and relatively high conversion foster front formation before the non-stationary one. Whereas, for T-i > T-a, steady-state frontal polymerization regime is established, when the heat flow from the outer source is considerably less than the heat evolving due to the chemical reaction. (C) 2009 Elsevier B.V. All rights reserved.