A new method for characterizing the geometry of open-cell foams is based on the construction of a digital signature through a morphological analysis of its digital image. This analysis involves the calculation of Minkowski functions of 2D binary images from transversal sections of solid foam. The digital signature proposed in this study has demonstrated a notable capacity of characterization and sufficient sensibility to distinguish morphologic characteristics of solid foams, a typical example of porous material. A practical use of the digital signature has been demonstrated establishing a relationship between morphologic variables and the effective mass transfer through solid foam; this signature could be a potential tool for predicting fluid transport parameters and other common physical phenomena in macroporous materials.