The modified Kozeny equation has been found to be satisfactory for the measurement of the specific surface of inorganic pigments having particle diameters of the order of 0.1 to 0.2 µ to within ±10%. These powders were too fine for visual microscope counting or standard sedimentation methods of specific surface measurement. The results obtained from experimental data were checked against those calculated from electron microscope counting for two of the powders studied and found to be in satisfactory agreement.