A particulate porous material suitable for use as a high surface area column packing material comprises particles substantially all of which are not smaller than 5 micrometers and not larger than 1 millimeter in diameter, and each particle is in the form of a substantially cellular body and consists predominantly of an open, three-dimensional matrix of crystals of mullite which define between them interconnecting pores having a width in the range of from 5 nanometers to about 2 micrometers. The particles can be coated with a reactive layer. There is also disclosed a process for producing the particulate porous material wherein a particulate product comprising particles substantially all of which are between 5 micrometers and 1 millimeter in diameter and consisting predominantly of a mixture of mullite crystals and silica is treated with a concentrated aqueous solution of an alkali metal hydroxide at a temperature of at least 50.degree. C.; and the treated particulate product is then washed, dewatered and dried. The particulate porous material may be used as a packing material for a chromatographic or ion exchange column, or for performing biochemical separations, and is particularly useful for immobilizing biological components such as biological macromolecules or biological cells.