The Zr + O-2 --> ZrO2 self-propagating high-temperature synthesis (SHS) has been investigated by computer simulation with a model accounting for two concurrent oxidation mechanisms (solid-state diffusion and gas-phase transport of oxygen) and for melting of reagent and product, under the external conditions defined by two process parameters: amount of zirconia added as diluent in the starting mixture (dilution degree) and partial pressure of oxygen reagent. The results are compared with those of a closely similar model that does not account for the phase transitions. Allowance for phase transitions shows many marked effects on the dynamic behavior of the SHS (which propagates in a steady mode under a wider range of dilution degrees) and on the macrokinetic parameters (space and time profiles of temperature and advancement degree of oxidation and time evolutions of wave speed and combustion temperature). These effects can be used for assessing the mechanism of an SHS from real experiments.