The 3-aminophthalic acid anion is a light emitter in luminol chemiluminescence. In the present study, the chemiluminescence of the 3-aminophthalic acid anion itself in the presence of hydrogen peroxide-cobalt (II) was studied. The results indicated that 3-aminophthalic acid anion is highly chemiluminescent in the typical hydrogen peroxide-cobalt (II) system. The peak wavelength of this chemiluminescence and the kinetic profile of the 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II) reaction showed similarity with that of luminol, but the chemiluminescence of 3-aminophthalic acid anion had a much lower background signal. In addition, the chemiluminescence mechanism of 3-aminophthalic acid anion-hydrogen peroxide-cobalt (II) was also discussed and speculated as the interaction between 3-aminophthalic acid anion and singlet oxygen.