The effect of the electrochemical potential of single-walled carbon nanotubes (SWCNTs) on the encapsulation behavior of (beta-carotene inside the SWCNT cavities was investigated by in situ Raman spectroelectrochemistry. Prior to Raman measurement, the electrochemical behavior of (beta-carotene at SWCNT electrodes was investigated. Weak adsorption of [beta-carotene was observed, whereas at glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) electrodes,beta-carotene showed diffusion-controlled reactions and was not adsorbed. Furthermore, a negative potential shift of the oxidation reaction of (beta-carotene was observed at the SWCNT surface corn pared with that at other carbon materials such as GC and HOPG. To remove the ends of SWCNTs to allow encapsulation of beta-carotene and minimize damage of the side wall of SWCNTs, we used finely controlled potential oxidation method. Results of the in situ Raman measurements indicated that encapsulation of (beta-carotene into the SWCNT cavity occurred most smoothly when a potential of 0.3 V (vs. Ag/Ag+) was applied to the SWCNTs. When the applied potential was >0.4 V, the encapsulated (beta-carotene could be oxidized and decomposed through formation of cation radical and dication forms ofp-carotene, even though the (beta-carotene was encapsulated in the SWCNTs. Applied potentials of-02 similar to 02 V did not result in smooth encapsulation compared with that at 0.3 V. Overall, we found that the encapsulation behavior of (beta-carotene in SWCNTs depended on the potential of the SWCNTs. (C) 2016 Elsevier B.V. All rights reserved.