The theoretical model of the steady state concentration and flux in immobilized glucose isomerase is discussed. This model is based on diffusion equation containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reaction. An analytical expression pertaining to the concentration and flux are obtained using the New Homotopy approach for all values of the dimensionless parameters φ _p (Thiele modulus) and β (kinetic parameter). Furthermore, in this work the numerical simulation of the problem is also reported using Scilab/Matlab program. The approximate analytical results are compared with the numerical results and found to be in good agreement.