An equation of diffusion for microcapsules(hollow sphere) was develope
d, employing the mathematical model for the diffusion characteristics
of solid sphere. In the proposed equation.a combination diffusion coef
ficient was introduced as a substitute for the diffusion coefficient i
n the solid.sphere mathematical model and expressed as a function of t
he diffusion coefficient inside solution of hollow sphere, as well as
in the polymer membrane. With this modified models the diffusion coeff
icients of glucose in NaCS (sodium cellulose sulfate)-PDADMAC(Poly-dia
llyl-dimethyl-ammonium chloride) membrane and in Ca-alginate gel membr
ane were determined. The diffusion coefficient in NaCS-PDADMAC membran
e was found to be 2. 12x10(-11) m(2).s(-1) and that in Ca-alginate mem
brane 2. 62 x 10(-10) m(2).s(-1).