Protein pores are being developed for use in biotechnology. [1] Many applications require that pores be stable at high temperatures. Herein we report single-molecule activity measurements on three proteinaceous membrane pores at temperatures close to 100 8C. We also show that one of the pores can bind a molecular adapter, b-cyclodextrin (bCD), at elevated temperatures. The complex retains the ability to recognize small molecules which permits stochastic sensing in aqueous solution under extreme conditions (Figure 1 a). The structures of many integral membrane proteins remain intact at high temperatures, [2] and the existence of extremophiles implies that membrane proteins function at 100 8C and above. [3] However, few measurements of membrane-protein activity have been made at temperatures above 55 8C, and none have been made for ion channels and pores. The photocycle of bacteriorhodopsin, for example, has been examined at temperatures up to 85 8C. [4] The activity is compromised above 60 8C because the chromophore, a transretinal Schiff base, isomerizes to the 13-cis form. Transmembrane proton pumping was not measured directly in these experiments. Macroscopic current recordings with valinomycin, a macrocyclic antibiotic, have been carried out at up to 80 8C in bilayers comprising lipids from the hyperthermophile Caldariella acidophila. [5] In the case of proteinaceous channels and pores, activity has been measured at up to 55 8C. For example, multichannel recordings of vanilloid receptors (temperature-sensitive cation channels) have been made after expression in Xenopus oocytes, and several subtypes of the receptor remain active at 55 8C. [6] Recently, [