A new method for setting the porous particle overall density is proposed. The apparent density of the particle including the solid matter as well as the different internal porosities (from microporous to macroporous pore size ranges) is currently needed for industrial applications as gas storage, heterogeneous catalysis... The technique proposed is based on the principle own immersion fluid applied to a granular medium consisting of extremely fine particles playing the role of non-wetting liquid. Here are presented the restrictive theoretical and experimental conditions, which have to be fulfilled by any granular medium before applying this principle. The conventional technique of mercury porosimetry has been used to characterize apparent grain density and validate the obtained results. The technique has been calibrated to be used with particles, which exhibit a different density, size, shape, and surface roughness. In a second part, the proposed method has been applied to a crop of materials including modified activated carbons previously obtained by oxidative transient treatments. The corresponding change in microporous properties has been studied by N-2 physisorption at 77 K. Moreover, the size ranges of the particle over which each technique leads to efficient measurements have been identified. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.