Abstarct: This work reports a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu (II) by flame atomic absorption spectrometry (FAAS). The method is baxsed on the on-line retention of copper at pH 5.0 on a minicolumn packed with the modified chloromethylated polystyrene by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT). The retained Cu (II) eluted with 1/0 mol L−1 HNO3 and introduced directly to nebulizer for determination. The influence of several chemical and flow variables were optimized for the quantitative preconcentration of copper (II) and a study of interference level of various ions was also carried out. At optimized conditions, the calibration graph was obtained linear over the concentration rang of 3.00–120. µgL−1 for 10 ml sample solution (4 min preconcentration time). The relative standard deviations (n=6) at 0.0040, 0.020 and 0.10 µgmL−1 levels for copper were 5.0%, 2.0% and 1.6%, respectively. The 3δ limit of detection and enrichment fator were 0.59 µgL−1 and 40 respectively. The method was applied to the determination of trace levels of Cu (II) in different real samples with satisfactory results.