The Generalized Global Equivalence Ratio Model (GGERM) was devolped to predict the generation rates of oxygen, fuel, and other products of combustion in rooms containing fires. The GGERM extends to general transient conditions the global equivalence ratio model established during times of steady state in experimental studies involving two-layer compartment fires. The present work uses the GGERM to predict upper layer mass fractions of products of combustion (fuel, oxygen, CO and others) in these two-layer fire experiments, but during times of transient response. All predicted results are found to be plausible and, where tranisent data are available, predicted and measured results compare favorably. However, available data are limited and additional validation of the GGERM under more varied fire conditions is required before it can be used with confidence in two-layer zone-type compartment fire models.