A rapid and sensitive flow injection method is presented for the determination of hydrogen peroxide with chemiluminescence (CL) detection. CL is produced by the oxidation of bis(2,4,6-trichlorophenyl) oxalate by hydrogen peroxide in the presence of a fluorescent compound, perylene. The emission was monitored with a purpose-built now injection CL detector. ?he responses between hydrogen peroxide concentration and CL intensity were linear over me range of (1 x 10(-9) M(-1) x 10(-5) M) with a cv. of 5.6% for 10(-9) M hydrogen peroxide and 4.6 for 1 x 10(-5) M hydrogen peroxide.