This work presents a study on the generation of an "anionic" potentiometric response of a liquid polymeric membrane based on calixpyrrole towards neutral chloro- and fluorophenol isomers. The results show that a calixpyrrole membrane is able to recognize chloro and fluoro derivatives of phenols, and discriminate between ortho-, meta-, and para-isomers of chlorophenol. The mechanism of molecular recognition relies on the formation of a supramolecular complex between a phenolic guest and the calixpyrrole host occurring at the organic/aqueous interface, which leads to a change of charge separation. The sensitivity and selectivity of the sensor studied depend on the acidity and lipophilicity of the phenolic analytes. The selected matrix effect on the potentiometric measurements has been checked.