Gel permeation chromatography has been performed using a porous glass of broad pore size distribution, which was subjected to hexamethyl-disilazane treatment. The elution volumes and peak widths of narrow molecular weight distribution polystyrenes using toluene as solvent have been determined. The physical characteristics of the porous glass have been studied by the methods of mercury porosimetry. nitrogen ad-sorption-desorption isotherms, and electron microscopy. The characteristics of this column packing material are compared with other packing materials in popular use.