Abstract: A new chemiluminescence method for the determination of nitrite in water is presented. This method is based on nitrite reaction with hydrogen dioxide solution with catalyst acid to create peroxynitrous acid. Peroxynitrous acid reacts with alkaline solution of luminol, producing chemiluminescence. The linear range for nitrite is 3.3×10-3to 3.3μg/mL with a detection limit of 1.6×10-3μg/mL, and the relative standard detection is 1.03% for 0.17μg/mL NO-2and 4.38% for 0.017μg/mL NO-2. This method has obtained satisfactory results in the analysis of natural waters.