A flow-injection chemiluminescence (CL) system is proposed for simultaneous determination of Co(2+) and Cu(2+) using partial least squares (PLS) calibration. This method is based on the fact that both Co(2+) and Cu(2+) catalyse the CL reaction of luminol-H(2)O(2), and that their kinetic characteristics of Co(2+) and Cu(2+) are significantly different in the luminol-H(2)O(2) system. The CL intensity was measured and recorder at different reaction times of luminol-H(2)O(2)Co(2+)Cu(2+), and the obtained data were processed by the chemometric approach of partial least squares. The experimental calibration set was composed of 16 sample solutions using an orthogonal calibration design for two component mixtures. The proposed method offers the potential advantages of high sensitivity, simplicity and rapidity for Co(2+) and Cu(2+) determination, and was successfully applied to the simultaneous determination of both analytes in real water sample. The present paper demonstrated that the simultaneous determination of two metal ions without any prior separation has been possible using flow-injection CL system.