Abatraet-The repassivating kinetics of Ni have been investigated by the abrading electrode technique. The early stage of repassivation kinetics of pure nickel have been studied as a.function of applied potential and Cl-ion concentration in 0.75 M Na,SO, solutions of pH 2.8. The applied potential and Cl-ion concentration ranged from -200 to 6OOmV,and from 0 to 0.2 M, respectively. Transition time tT at which current decay transients intersect for given applied potentials decreased with increasing applied potential. In the absence of the Cl-ion, the current decay rate increased with increasing applied potential from 0 to f5OOmV,, . As the Cl-ion concentration increased at a given applied potential, the current density increased below t,, whereas it decmased above t.r. The repassivation kinetics with respect to the Cl-ion have been discussed in terms of competitive adsorption of Cl-and OH-/02-ions. As a result it is suggested that below t,, the increased current density by the addition of Cl-ion is caused by the preferential adsorption of Cl-ion and the inhibition of the adsorption of OH-ion on the nickel surface. Above t,, the decreased current density by the addition of Cl-ion is based upon the fact that the adsorbed Cl-ion facilitates the place exchange reaction between metal and hydroxyl ions, and hena the film formation.