The simultaneous optical readout of a potentiometricsensor array of ion-selective electrodes (ISEs) based on PVCmembranes is described here for thefirst time. The optical arrayconsists of electrochromic Prussian Blue (PB)films in multiple closedion-selective bipolar electrodes (BPEs), which gives a physicalseparation between the optical detection and sample compartments.The potential-dependent turnover of PB generates Prussian White(PW). A near-Nernstian response of the PBfilm is confirmed bycolorimetric absorbance experiments as a function of applied potential.In the combined bipolar electrode cell, the overall potential is keptconstant with a single potentiostat over the entire array where each PBspot indicates the potential change of an individual connectedpotentiometric probe. For cation-selective electrodes, the absorbance or blue intensity of the connected PBfilm is enhancedwith increasing target cation activity. The colorimetric absorbance changes are simultaneously followed by a digital camera andanalyzed by Mathematica software. A multiple cation-BPE array allows one to achieve simultaneous quantitative analysis ofpotassium, sodium, and calcium ions, demonstrated here in highly colored fruit juices. Mass transport at the PB thinfilm is shownnot to be rate-limiting. The measuring ranges can be tuned in a wide range by potential control. The PBfilm exhibits greatlyimproved reproducibility and stability as compared to previous work with a ferroin redox probe confined in a thin solution layer.