The invention relates to a monolithic porous material made of amorphous silica or activated alumina, comprising substantially rectilinear capillary channels that are parallel to one another, wherein: the channels have a substantially uniform cross-section relative to each other, the cross-section of each channel is regular over its entire length, the channels pass through the material from end to end, the length of the channels is equal to or more than 10 mm. The invention also relates to an annular, radial or axial chromatographic apparatus, the packing of which consists of at least one said monolithic material.The invention also relates to processes for manufacturing such a monolithic material.