AbstractThe interaction of three organic compounds (benzene, methanol, and N, N′‐dimethylformamide) with cellulose was examined, and an attempt was made to relate the extent of interaction with cellulose structure and the molecular structure of the organic compound. The observed interaction between cellulose and benzene, methanol, and DMF is consistent with the idea that the extent of interaction is a function of size and hydrogen‐bonding ability of the swelling liquid. The surface areas, obtained from the vapor isotherms, indicate that the interaction is in the order benzene < methanol ≈︁ DMF. Heats of adsorption determined for the three vapors on cellulose are in good agreement with literature values obtained from calorimetric heats of wetting and, when compared with heats of hydrogen‐bond formation for model systems, indicate that the interaction must involve hydrogen‐bond formation. The heats of adsorption indicate that in the case of methanol and DMF the hydrogen‐bond formation extends over a wide range of vapor coverage, while for benzene vapor the hydrogen‐bond formation falls off rapidly after completion of a monolayer. Limited swelling measurements indicate that the heat of adsorption may be more important than the size of the swelling liquid molecule in the early stages of swelling, but after all the high‐energy sites in the cellulose (attributed to mechanical strains induced in the fiber on drying or processing) become saturated, the size of the molecule becomes more important in determining the extent of swelling.