A cyclodextrin-peptide hybrid (17NNbeta) bearing two naphthalene units in the peptide side chain has been designed and synthesized as a novel chemosensor molecule. Circular dichroism study of the compound the peptide has alpha-helix structure with a helix content of 41%. The peptide revealed both monomer and excimer emission and the intensity of the excimer increased while that of the monomer emission decreased upon addition of the guest compound. This behaviour was observed for various guest molecules, suggesting that the system can be used for detecting molecules in aqueous solution.