In a short runtime process (about 10 minutes), with the isocratic method, a mixture of some degradation molecules and Mexiletine.HCl was separated and detected by means of an UVVis/HPLC system. A good chromatography separation was performed on Bonda pack C18 300 x 3.9 mm 10µm with mobile phase consisted Methanol: Anhydrous sodium acetate buffer in the ratio of 60:40(v/v), respectively. The Mexiletine.HCl assay shows a linear (r2 = 0.999) calibration range over the concentration range of 1000 - 3200μg/mL of analyte concentration. The method was precise (%RSD < 1)) and accurate, with recovery in the range 99.63% - 100.22%. LOD was found to be 18μg/mL and the LOQ value was found to be 59.4μg/mL. Moreover, the method was successfully used for the separation of Mexiletine.HCl from its degradation product. The method was validated as per ICH guidelines, and the investigated results of the validation processes showed that the method was trustworthy enough to be routinely used in laboratories.