An isotherm quasi-discontinuity, or a near-vertical step, at 177 mu Torr indicative of Kr condensation inside open single-walled carbon nanotubes (SWNT) has been observed at 77 K. The isotherm shows double adsorption-branch structure attributed to the existence of two endohedral phases of confined Kr. Three well-pronounced steps corresponding to the formation of various exohedral phases are present in the high-density (low-pressure) branch. The desorption branch exhibits three rounded steps assigned to higher order exohedral coverage.