The effect of liquid-phase nonideality on intraparticle transport with chemical reaction is explored theoretically and experimentally. Generalized transport equations for the multicomponent diffusion and flow of n species participating in q reactions are developed on the basis of the dusty-fluid model, in which the diffusional driving force of species i is its chemical potential gradient. This is appropriate owing to the nonideality of reaction mixture and is consistent with the thermodynamics of irreversible processes. Nonideality also impels the use of species activities as a measure of composition in the reaction rate expression. The constitutive equations are generally supplemented by n material balances, but because of stoichiometry, only q of these are independent. The n "species" fluxes in the material balance and constitutive equations are, therefore, replaced by an independent set of q "reaction" fluxes, resulting in a simpler and more direct description. This transport and reaction model is applied to the case of liquid-phase synthesis of ethyl tert-butyl ether (ETBE) under isothermal conditions. The model is experimentally validated for a variety of conditions, providing good agreement between theory and experiments without the use of any adjustable parameters.