A method for the simultaneous spectrophotometric determination of iron and copper by flow-injection analysis was developed using 2-(5-bromo-2-pyridylazo)-5-( N-propyl- N-sulphopropylamino)aniline. The flow system utilizes a double-beam spectrophotometric detector with two flow cells. The reagent forms water-soluble chelates with Cu(II) and Fe(II) in an acetate-buffered medium at pH 4.5. The molar absorptivities of the complexes are 65 000 l mol −1 cm −1 at 578 nm for Cu(II) and 87 000 l mol −1 cm −1 at 558 nm for Fe(II). In one reaction coil Fe(II) is oxidized to Fe(II) by KIO 4, so the Fe(II) chelate is not formed and only the coloured complexes with Cu(II) are monitored in the first flow cell. In a second reaction coil, the solution merges with sodium ascorbate solution to reduce Cu(II) and Fe(III) to Cu(I) and Fe(II). Thus only the Fe(II) complex is measured in the second flow cell. Cu(II) and Fe(II) in the range 50–200 μg l −1 are determined at 558 nm. The sample throughput is 30 h −1 with a precision of 1.2%