To develop sensitive and selective S(2-) chemosensors, a new disubstituted polyacetylene (P2) bearing pyridine moieties in the side chains was prepared conveniently through a postfunctional method, the strong green fluorescence of which could be completely quenched by Cu(2+) ions at the concentration as low as 2.0 x 10(-6) mol/L in diluted solutions. Based on the displacement strategy, by utilizing the much higher stability constant of the complex of S(2-) and Cu(2+) the quenched fluorescence of the solution of P2 by Cu(2+) ions could recover upon the addition of trace S(2-) anions, with the detection limit down to 5.0 x 10(-7) mol/L. Moreover, no interference were observed from other anions, including SO(3)(2-), HSO(3)(-), SO(4)(2-), ClO(4)(-), I(-), Br(-), Cl(-), F(-), IO(3)(-), HPO(4)(2-), PO(4)(3-), C(2)O(4)(2-), S(2)O(3)(2-), CO(3)(2-), AcO(-), CN(-), and P(2)O(7)(4-), making P2 a novel, sensitive, and selective sulfide probe.