The adsorption properties of the MWW compositional end member, ITQ-1, have been explored empirically and via computer simulation using n-hexane, 3-methylpentane, 2,3-dimethylbutane, p-xylene and ethylbenzene as adsorbate probes. n-Hexane and 3-methlypentane diffuse rapidly and both have a sorption limit of four molecules per unit cell, three of which are in the large channel cavities. 2,3-dimethylbutane sorbs more slowly through the 10-ring windows; the limiting three molecules per unit cell are all in the large cavities. The two aromatics adsorb in both channel systems, with p-xylene diffusing rapidly and ethylbenzene more slowly but much faster than 2,3-dimethylbutane. No clear distinction between intra- and extra-crystalline adsorption was observed. Computer modeling indicated distinctions between the two channel systems.