A solvent-soluble membrane filter is proposed for a simple and rapid preconcentration and spectrophotometric determination of iron (II), which was collected on a nitrocellulose membrane filter as an ion-associate of the cationic complex of iron (II)-1,10-phenanthroline with an anionic surfactant of dodecyl sulfate. The ion-associate collected was dissolved in 5 ml of 2-methoxyethanol together with the filter. The color intensity due to the ion-associate in the resulting solution was measured at 510 nm against a reagent blank. Beer's law is obeyed in the range 1–15 μg Fe (II) in 5 ml of solvent with excellent reproducibility, and detection limits better than 0.5 μg dm−3as Fe (II) can be achieved. The diverse components normally present in water do not interfere when proper masking reagent is added. The proposed method has been applied to the analysis of water samples from several sources such as river water, ground water and tapwater samples, the recoveries of the iron (II) added to the samples are quantitative, and results found are satisfactory.