The paper below is devoted to the presentation of an experimental technique that allows the structural characterisation of a porous medium that possesses a two-sided structure. The first part of the paper describes the experimental method, which Is based on the classical mercury intrusion technique. The characterisation at the porosity including both the bulk and the surface porosities is highlighted. The specific surface can also be estimated, enabling the calculation of the mean hydraulic diameter. The second part of the paper describes how the technique can be used to determine the two-sidedness effect, i.e. the porosity of each face can be estimated. In order to illustrate the developed technique, experimental examples using paper samples are presented. Finally a conclusion is drawn relating to the structural properties that can be determined using this method.