A time-resolved chemiluminescent method for the determination of pyruvic and tartaric acid has been developed. The method is based on the differential rate of the chemiluminescent reaction of Ru(bipy) 3 2 + , pyruvic and tartaric acid with Ce(IV). The pyruvic acid system gives the highest chemiluminescence intensity at 2 s, whereas the tartaric acid system gives its most intense chemiluminescence emission at 64 s. Pyruvic acid (6.0x10 - 6 ~1.1x10 - 8 M) and tartaric acid (3.7x10 - 4 ~1.3x10 - 6 M) were determined simultaneously with relative standard deviations greater than 4.5% (n=10). The detection limit of pyruvic acid and tartaric acid were 7.0x10 - 9 M and 2.7x10 - 7 M, respectively. The method was evaluated by carrying out a recovery study in human serum. A satisfactory result was obtained.