X- ray photoelectron spectroscopy (XPS) along with inductively coupled plasma analysis (ICP-AE) and Raman spectroscopy have been used to define the location and to quantify the amount of iodine in HiPco SWNT samples loaded with molecular I-2 via sublimation (I-2-SWNTs). The exterior-adsorbed I-2 can be removed (as I-) by reducing the sample of filled nanotubes with Na-0/ THF or by heating the I-2-SWNTs to 300 C (without reduction), leaving I-2 contained only within the interior of the SWNTs (I-2@ SWNTs) as proven by XPS. These I-2@ SWNTs contain similar to 25wt % of I-2 and are stable without the loss of I-2 even after exposure to additional reduction with Na0/ THF or upon heating to ca. 500 degrees C.