Provided herein are methods for dehydrating single-walled metal oxide nanotubes by heating the SWNT under vacuum at 250-300° C.; methods of dehydroxylating SWNT, comprising heating the SWNT under vacuum at 300-340° C., and methods for maximizing the pore volume of a SWNT, comprising heating the SWNT at 300° C. under vacuum to partially dehydroxylate and dehydrate the SWNT; methods of modifying the inner surface of a single walled aluminosilicate nanotube (SWNT), comprising dehydration or dehydration and dehydroxylation, followed by reacting the SWNT with a derivative under anhydrous conditions to produce a SWNT that is derivatized on its inner surface. The invention also includes single-walled nanotubes produced by the methods of the invention.