Abstract: Large amounts of calculations on effectiveness factor have been done based on the approximateexpression proposed in Part(Ⅰ)of this work for porous catalyst under isothermal condition at various valuesof Thiele modulus for nonfirst order reaction of power-function and hyperbolic kinetics.Likewise,valuesof effectiveness factor have been obtained under the same conditions from the three expressions found inliterature as well as by numerical method for comparison.The results show that our approximate expressionhas a quite high accuracy and therefore is much superior to the others.The parameter estimation of ourexpression is rather easy doing and has no such difficulties as encountered in handling of the other ex-pressions.