Through flow injection analysis experiments, it was discovered that unsaturated complexes of Cu(II) with proteins had a much stronger catalytic effect on the luminol–H2O2chemiluminescence reaction than did Cu(II). Based on this, a new rapid and sensitive method for determination of some proteins in the range 0.1–20.0 μg ml−1was established. The detection limits were at the 0.03–0.05μg ml−1level for bovine serum albumin (BSA), human serum albumín (HSA), human γ–globulin (γ–G), and egg albumin (EA). The method was used for the determination of proteins in human serum with satisfactory results.