In the present paper a dynamic model has been developed to calculate the critical front velocity of the pushing-engulfment transition (PET) during production of MMCs. The model is the extension of our recent steady state model [G.Kaptay: Metall.Mater.Trans.A., Vol. 32A (2001) p. 993]. It has been shown that there is no dynamic effect during PET. The theoretically determined critical front velocity for the Al/ZrO2 (R = 250 mum) system (0.67 mum/s), is within the experimentally determined interval of this value (being between 0.5 and 1.0 mum/s), found under microgravity conditions in [D.M.Stefanescu, F.R.Juretzko, B.K.Dhindaw, A.Catalina, S.Sen, P.A.Curreri, Metall. Mater. Trans. A, Vol. 29A (1998) p. 1697].