A new bridge-building technique was used for facilitating H spillover on metal doped adsorbents for hydrogen storage at room temperature. By preadsorbing 1.0 x 10(-3) atm of CH4 on Pt/AX-21 (superactivated carbon), the adsorbed amount of hydrogen increased by. similar to 100% at 1 atm and 25 degrees C, attributed to the adsorbed CH4 serving as bridges for spillover. We conclude that the Benson-Boudart method can provide a good assessment for the dispersion of metals supported on Al2O3 (and zeolites). For carbon and SiO2 supports, even with pure H-2, spillover leads to overestimates of dispersion, and any small amounts of gaseous impurities could lead to much greater overestimates. (C) 2008 Elsevier Inc. All rights reserved.