The effect of micromixing on steady-state multiplicity is not displayed by the universal reaction model (URM) since this URM has considered any chemical species having the same mixing time constant. The modified universal reaction model(MURM) is derived for overcoming the above limitation. The design equations are first derived. Furthermore, the MURM is employed for studying the effect of micromixing on the multiplicity for autocatalytic, isothermal reactions of the type A + B --> (eta + 1)B + product with the overall rate expression being - gamma(a) = kC(a)(p)C(b)(r) in a CSTR. The effects of micromixing on necessary and sufficient conditions for multiplicity are presented.