Cesium is a common contaminant in industrial, medical, and nuclear wastes, and can cause several health problems. Therefore, the development of chemical probes and absorbents for cesium is important for the medical, biological, and industrial fields. Herein, we report the sensing ability of tri-or dihydroxylphenyl-appended benzenetricarboxyamides (BTAs 1 and 2, respectively) as chromogenic probes for cesium ions. Compounds 1 and 2 form self-assembled nanofibers spontaneously in aqueous solution, which is attributed to the intermolecular hydrogen-bonding interactions of the triamide groups in the BTA core. The color of 1 and 2 in aqueous solution changes from colorless to yellow upon addition of Cs+, but not any other metal ions. H-1 NMR observation reveals that compound 1 forms a complex with Cs+ through cation-pi interactions. In addition, the nanofiber structures of 1 and 2 adopt spherical morphologies upon addition of Cs+. To develop a portable cesium sensor, a fiber incorporating 1 (EF-1) is fabricated by the electrospinning method. EF-1 exhibits high affinity and selectivity for Cs+ over other competing metal ions. Therefore, EF-1 shows promise as a portable sensor for the detection of Cs+ in aqueous solution. (C) 2017 Elsevier B.V. All rights reserved.