The rate-enhancing strategy of microphase catalysis utilizes a microdispersed phase which shows a high affinity for the diffusing (rate-limiting) solute. When an intermediate/product constitutes the microphase, the rates computed on the basis of a quasi-steady-state theory of microphase catalysis are underpredicted. Mathematical models, utilizing a simplified population balance approach in the "film zone", have been developed to determine the extent and nature of the transient effects due to the microphase, which are ignored in the quasi-steady-state versions. Thus, an attempt has been made to focus on the "near interface effects" of the precipitating microphase. It has been demonstrated that these effects are of tremendous significance.