A membrane responsive to nitrite has been developed which is composed of plasticized PVC, the anion carrier benzylbis(triphenylphosphine) palladium(II)chloride, and the potential-sensitive dye (PSD) rhodamine B octadecyl ester perchlorate. On exposure to nitrite, fluorescence intensity increases, while the wavelengths of both the excitation and emission maxima remain unchanged. The sensor membrane exhibits its highest sensitivity to nitrite in the 5 to 5000 mg l^–1 range, and the detection limit is 0.5 mg l^–1. The signal change on exposure to 100 mmol l^–1 nitrite is as high as +95%. The effect of pH is significant: from pH 5.0 to pH 9.0 and in the absence of nitrite, the fluorescence intensity changes almost linearly by around –9% per pH unit. In addition, the sensor is cross-sensitive to pH: the relative signal change from plain buffer to 1 mmol l^–1 nitrite is smaller by 65% at pH 9.0 than at pH 5.0. The selectivity coefficients relative to nitrite were determined by the separate solution method at pH 7.13 and were found to be 8 × 10^–3 for nitrate, 1.6 × 10^–3 for chloride, 8 × 10^–4 for hydrogencarbonate, and 3 × 10^–4 for sulfate. The lifetime of the sensor membrane is limited by leaching of the PSD, which is in the range of 1–3% h^–1.