The adsorption of N-2 on the open-ended single-walled carbon nanotube bundles was studied. The amount corresponding to the first coverage adsorbed on open-ended carbon nanotube bundles is three times larger than the amount adsorbed on closed-ended nanotube bundles. The isosteric heat of adsorption was obtained from the adsorption isotherm measurement performed at temperatures ranging from 117 to 130 K. The estimated heat of adsorption of nitrogen on the open-ended nanotube bundles is about twice as great as that on the closed-ended nanotube bundles. This leads directly to the conclusion that the binding energy of nitrogen on the open-ended nanotube is greater than that of nitrogen on the closed-ended nanotube bundles.