AbstractI3−‐selective electrodes with a PVC membrane containing ionic associates of crystal violet (CV) triiodide as electrode‐active substance were developed. The pH working range is 2–12, the linearity range of the electrode function is 9×10−6–1×10−1 mol/L, and the electrode function slopes are varying from 44.0 to 62.0 mV/decade, depending on the plasticizers in the membranes. The efficiency of the use of these electrodes for dibenzoyl peroxide and magnesium monoperoxyphthalate determination in pharmaceutical preparations was shown by potentiometric titration methods.