The heterogeneous photocatalytic oxidation of nitrite ion using suspension TiO2 photocatalyst is investigated. Experimental results indicate that bubbling air through the solution promotes the photocatalytic reaction. The adsorption of reactant on photocatalyst is significant in photocatalytic oxidation of nitrite ion as well. Under an alkaline condition, a semitheoretical kinetic rate equation, R-i = 2.36 x 10(-4)[TiO2](0.12)[NO2-][OH-](-0.30), is obtained in dilute NO2-solution. Under an acidic condition, the photocatalytic oxidation rate of NO2- can not be measured or be determined exactly. In a 1 similar to 3% dilute NaCl solution, Cl- ion only slightly affects the photocatalytic reaction. Moreover, the Cl- ion cannot promote the photocatalytic oxidation of nitrite ion. Furthermore, the photooxidation removal percentage of nitrite ion in the presence of 0.51 M of Cl- solution is only 85% of the system without Cl- ion.