Xenon adsorption studies were performed on aggregates of single-walled carbon nanohorns (SWNHs). The SWNHs were prepared in two different batches; the adsorption results from the two batches were essentially identical. Isotherms were performed in two groups of experiments: low-coverage data were used to measure the binding energy of Xe on the SWNHs; and full isotherms were measured to determine specific surface areas. The binding energy value for Xe on the SWNHs was intermediate between those for Xe on single-walled carbon nanotubes, and that for Xe on graphite. The specific surface area of the SWNHs was of the order of 250 m2 g-1.