Activated carbon loaded with xylenol orange in a mini-column was used for the highly selective separation and preconcentration of Pb(II) and Cd(??) ions. An on-line enrichment followed by flame atomic absorption spectrometry was used for determination of Pb(II) and Cd(II) in water sample. The conditions of preconcentration and quantitative recovery of Pb(II) and Cd(??) from diluted solution, such as pH of aqueous phase, acidity of elution phase, the amount of the sorbent, the volume of the solutions and flow variables were studied as well as effect of potential interfering ions. Under the optimum conditions, Pb(II) and Cd(??) in an aqueous sample was concentrated about 200 and 250-fold, respectively. The relative standard deviations (RSD) were 3.99% for 200 ng mL -1 Cd(II) and 5.45% for 400 ng mL -1 Pb(II) (n=6). Lead(II) and cadmium(??) recovery from river water, waste water and tap water was obtained in the range of 99%-104% by the methods. The detection limit of 1.2 ng mL -1 for Pb(II) and 0.3 ng mL -1 for Cd(??) was achieved.