A separation/preconcentration of aluminum (III) (Al 3+) has been developed to overcome the problem of high matrix species, which may interfere with the determination of trace quantity of Al 3+ in natural water samples. The separation of Al 3+ in water samples was carried out from interfering cations by complexing them with 2-methyle 8-hyroxyquinoline (quinaldine) on activated silica. Whereas the separated trace amounts of Al 3+ was preconcentrated by cloud point extraction (CPE), as prior step to its determination by spectrofluorimetry (SPF) and flame atomic absorption spectrometry (FAAS). The Al 3+ react with 8-hydroxyquinoline (oxine) and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of separation/preconcentration of Al 3+ was checked by certified reference material of water (SRM-1643e). After optimization of the complexation and extraction conditions, a preconcentration factor of 20 was obtained for Al 3+ in 10 mL of natural water samples. The relative standard deviation for 6 replicates containing 100 μg L −1 of Al 3+ was 5.41 and 4.53% for SPF and FAAS, respectively. The proposed method has been applied for determination of trace amount of Al 3+ in natural water samples with satisfactory results.