Immobilization experiments have been performed with glucose oxidase as enzyme and controlled-pore glass of different pore sizes as support for chemical coupling. The experimental results have been analyzed for comparison with the theoretical model predictions. Analysis of the initial stage of the process gives the fundamental characteristic of the immobilization reaction. These investigations allow us to study the influence of the degree of diffusional restriction on the evolution of the immobilization process and spatial distribution of immobilized enzyme. Nonuniformly distributed concentrations have been achieved within the porous matrix, and suggestions have been made in designing such profiles by choosing appropriate experimental parameters.