This paper reports a new and simple approach for the amplified detection of flouride ions by a polymer-based chemosensor made of stiff fluoroalkylated polysilane, poly(3,3,3-trifluoropropylmethylsilane). This chemosensor exhibited extreme sensitivity and selectivity towards fluoride ions by a decrease in the photoluminescence (PL) intensity with parts per billion concentration of flouride ions in solution in tetrahydrofuran (THF). The quenching constant for flouride ions (K = 1.35 x 10(7) m(-1)) was found to be exceptionally high.