Adsorption isotherms of n-pentane to n-decane were measured gravimetrically on silicalite crystals at temperatures ranging from 30 to 150 degrees C and at pressures up to 1333 Pa. The virial equation was used to correlate the experimental data and to calculate the Henry’s law constants and the heats of adsorption at zero loading. The limiting heats of adsorption of hexane and heptane are slightly higher than those reported in literature. The isotherms of these two compounds also exhibit an unusual convex region in a certain temperature range. The saturation capacities decrease from pentane to decane with a significant drop observed from heptane to octane.