Potential use of a surfactant-like receptor is demonstrated at the 1,2-dichloroethane-water interface for strong and selective binding of H 2 PO 4 - over Br - and Cl - . The analysis by interfacial tensiometry reveals that the interfacial adsorption of a thiourea-isothiouronium conjugate, BT-C 1 , is significantly stabilized by the binding of H 2 PO 4 - with the adsorption constant of 1.7x10 5 M - 1 while the interfacial adsorptivity of this receptor is relatively moderate for Br - (0.81x10 5 M - 1 ) and Cl - (0.63x10 5 M - 1 ). Such complexation-induced interfacial adsorption behaviors of BT-C 1 are discussed as a basis for the development of receptor-based chemical sensors for phosphate anions.