This article deals with the development of flow injection system for the spectrophotometric determination of Hydroquinone drugs. The analytical system is based on oxidation reaction using KMnO4 as oxidizing agent for conversion of HQ to P-benzoquinone (BQ) in an alkalinemedium,the absorbance is measured at 610nm .All different chemical and physical experimental parameters affecting on the development and stability of the colored product were carefully studied. The parameters optimized by using 20 μg.ml-1 standard solution of HQ. Beerˊs law is obeyed over the concentration range of 1-26 and 3-125μg.ml-1of Hydroquinon with detection limits of 0.0125 and 0.25 μg.ml-1 of Hydroquinone for spectrophotometric and FIA- Merging zone, respectively. The color product formed by passing of a 0.1 M sodium hydroxide as carrier at flow rate of 2.12ml.min-1 is merged with a volume of 227.65 μL of sample and the volume of 227.65 μL of oxidant agent to conclude a final methodology for the determination of HQ accommodating 227.65μL as injection sample. Under these Conditions, the FIA system allowed to analyze was about 55 samples per hour .The method was successfully applied to the determination of HQ in Pharmaceutical formulations without any interference from common excipients used as additives .The results agree favorably with standard method.