A sensitive and accurate Sequential Injection Analysis technique for determining Cupper (II) ion in different samples, using a new azo derivative reagent of 8-hydroxy quinoline (HQDABA). The reagent and Cu(II) complex diagnosis included Infrared spectroscopy, Ultraviolet-Visual radiation, Elemental Analysis (CHN), Energy dispersive X-ray spectroscopy (EDX), nuclear magnetic resonance spectroscopy 1HNMR and mass spectroscopy techniques. The method depends on the reaction of Cupper (II) with the (Azo derivative of 8-hydroxy Quinoline) reagent in a neutral medium to form a Brown complex which gave a maximum absorbance at 420 nm. The optimum conditions such as flow rate, Copper (II) volume, reagent volume; pH, reagent concentration, and reaction coil length are thoroughly examined. A Copper (II) curve is constructed, and the suggested method obeys Beer's law over ration range of 1-10 mg/ L. The limits of detection (LOD) and on (LOQ) are determined to be (0.361) mg/ L and(1.204) mg/ L, while Sandell's sensitivity and molar absorption coefficient are to be (0.120) µg/ cm2 and (527.05) L/ mol. cm respectively. The recommended method has given good accuracy with recovery rates ranging from (77.82% - 115% ).