The objective of this project was to demonstrate the validity of the analytical method for the determination of Diclofenac present in drinking water, developed at the Mexican Institute of Water Technology (IMTA) in the Subcoordination of Water Quality, in the area of Liquid Chromatography. The method was validated following a previously elaborated work methodology, where different parameters such as linearity, accuracy, precision, selectivity, detection and quantification limits, system suitability and solution stability were analyzed. Satisfactory results were obtained, thus proving the validity of the analytical method.