An equation of diffusion for microcapsules(hollow sphere) was developed, employing the mathematical model for the diffusion characteristics of solid sphere. In the proposed equation.a combination diffusion coefficient was introduced as a substitute for the diffusion coefficient in the solid.sphere mathematical model and expressed as a function of the diffusion coefficient inside solution of hollow sphere, as well as in the polymer membrane. With this modified models the diffusion coefficients of glucose in NaCS (sodium cellulose sulfate)-PDADMAC(Poly-diallyl-dimethyl-ammonium chloride) membrane and in Ca-alginate gel membrane were determined. The diffusion coefficient in NaCS-PDADMAC membrane was found to be 2. 12x10(-11) m(2).s(-1) and that in Ca-alginate membrane 2. 62 x 10(-10) m(2).s(-1).