The invention relates to a monolithic porous material based on amorphous silica or activated alumina or on one of their mixtures, the material comprising substantially rectilinear capillary ducts that lie parallel to one another, and being intended to be used as packing in a chromatography column, characterised in that: the ducts have, relative to one another, a substantially uniform cross section; the cross-section of each duct is uniform over its entire length; the ducts pass right through the material; the volume of micropores smaller than 0.3 nm is smaller than 50% of the total porous volume of the material.