Extensive simulations indicate that in most but not all cases the single- and two-phase models predict similar dynamic behavior of a reverse-flow reactor; when catalyst pellet multiplicity does nor occur at any point in the reactor. Differences in the predictions are found in some cases close to the dynamic bifurcation loci of a cooled RFR, or in others when the qualitative dynamic behavior is very sensitive to the value of the parameters, such as close to a transition to chaotic behavior. The two models can lend to rather different predictions of the dynamic features when there are large differences between the feed and coolant temperatures.