Abstract : In fiber reinforced polymeric matrix, stresses are transferred from the matrix to the reinforcement through a 3D zone called interphase. Its properties result from the physicochemical interactions of components. Two difficulties arise: first, the need to study the interphase once the composite is manufactured and second, its size that varies from a nanometer to few micrometers. The study aims at developing a mechanical properties characterization technique of a microcomposite interphase. Strain fields, given by a numerical derivation from displacement fields, are computed by the virtual fields method in order to identify the rigidities of the interphase material. Two experimental techniques have been developed to measure the displacement field in the interphase during a tensile test: the adaptation of the moiré interferometry with a phase stepping method (micrometer spatial resolution) and the digital image correlation with a far-field microscope (subpixel analysis). A comparison is made between these two techniques applied on this study. The strain field is analyzed through the virtual fields method to determine the parameters governing the interphase constitutive law.