A mixture of the Pd(II) complex [Pd(NO3)2(bipy)] (bipy = 2,2-bipyridine) and the fluorescent dye Methylcalcein blue (MCB) constitutes a chemosensing ensemble which can be used for the detection of pyrophosphate (PPi) by fluorescence spectroscopy. The sensor operates in buffered aqueous solution at neutral pH, and allows sensing PPi at low to mid micromolar concentrations with very good selectivity over other anions such as phosphate, acetate, nitrate, sulfate, chloride, and bicarbonate.