A deterministic based analytical model has been developed to study the mass transfer characteristics between the reactants in a liquid- liquid parallel flow microchannel reactor. Since each phase is continuous and parallel to each other, the interface between the phases is well defined. Convection and diffusion mass transfer mechanisms with a third order reaction is considered for the design of single dimensional deterministic model. The model is developed by considering the transport phenomena of the system and solved with the help of pdepe solver in Matlab 7.6.0. The effects of residence time with various concentration profiles are discussed. The study reveals that the concentrations of desired and undesired products mainly depend on the flow velocity and concentration gradient of the reactants. The time required for the equilibrium is inversely proportional to the pseudo mass transfer coefficient of the system.