A theoretical model for the dependence of the modulus of elasticity, M, on the porosity, alpha, of an elastomeric disk subjected to triaxial stress was developed. An empirical law was proposed for the dependence of the surface energy, Gamma, on the porosity, alpha, of the elastomer. The presented theoretical model is a two-degree-of-freedom model, the parameters of which are determined by fitting with experimental data derived from the elastomer disks. In order to obtain the final mathematical expression for the effective modules of the composite system, a relationship between the strain field within the disk and the porosity was developed. The numerical differentiation of the experimental stress/strain curve from the tested bonded elastomer disks yields the values of the apparent modulus of the elastomer disks as a function of the strain field within the testing specimens. An appropriate combination of the proposed theory and the received experimental data yields the percentage of the growing microvoids within the deformed material.