[en] Accuracy and reliability of the analytical results are crucial for ensuring quality, safety, and efficacy of pharmaceutical products. However, to ensure these criteria, analytical validation is required. In this matter, many official documents describing the criteria of validation are available. However, these concern mainly chromatography analysis and bio-analytical methods of pharmaceutical products, but they do not propose any experimental protocol for direct potentiometric methods using ion-selective electrodes applied in pharmaceutical analysis. In this work, we are proposing a validation strategy based on the normative and regulatory guidelines applied to a potentiometric method with a polymeric membrane selective to cetirizine dihydrochloride. The statistical analysis obtained from raw data is described for all steps of this protocol. Also this validated method was successfully applied to the determination of cetirizine in pharmaceutical preparations using direct potentiometry with a mean relative standard deviation of 0.57% and a mean recovery of 99.63%.