Polycyclic aromatic 1-pyrenecarboxylic acid (2) was investigated as an anion selective probe by means of UV-vis and fluorescence titrations in CH3CN. Acid 2 showed stronger affinity and higher selectivity to HPO42-and SO42- over monovalent anions, such as F-, Cl-, Br-, H2PO4-, ClO4-, HSO4-, NO3-, BF4-, and PF6-. Complete fluorescence quenching upon complexation of acid 2 with HPO42- and SO42- was successfully observed by the eye.