A solid peptide nanotube material based on the self-assembled heptapeptide Ac-KLVFFAL-NH₂ (KL-7) was demonstrated to be capable of selective chemisorption of carbon dioxide. The selective adsorption resulted from the chemical reaction of carbon dioxide with the amino group exposed on the KL-7 nanotube surface, with this reaction shown using solid-state NMR to have formed carbamate. The KL-7 nanotube powder showed good regeneration properties and was effective in the presence of water.