The kinetics of the interaction of ground-state Cl(P-2(3/2)) and spin-orbit-excited Cl(P-2(1/2)) atoms with polycrystalline nickel surfaces has been studied in a very low pressure (approximately 1 mTorr) reactor. The atoms are produced outside the Knudsen cell in a pulsed atom source and allowed to react with the sample surface at different temperatures (295 to 750 K). Time-resolved resonance-enhanced multiphoton ionization (REMPI) was employed to monitor the time-dependent number density of Cl atoms in situ, both in the presence and the absence of the Ni surface. On-line effusive beam mass spectroscopy was used to calibrate the REMPI signal. The decay of the spin-orbit-excited Cl* density was a simple exponential decay corresponding to an initial sticking coefficient, gamma-o, of (1.0 +/- 0.1) x 10(-2). Ground-state Cl showed a complex decay behavior that was fitted by using a chemical kinetics model, resulting in gamma(o) = (1.5 +/- 0.5) x 10(-2). The kinetic simulation suggests a weakly bound precursor state for Cl, which is bound by 3.9 kJ/mol and interacts with the strongly bound adatom state. REMPI signals taken after repeated exposure of the Ni specimen to pulses of Cl revealed a pronounced capability of that surface to store atomic Cl. At our pressure/temperature conditions (up to 10(13) Cl/cm3, 300 to 750 K), the passivation of Ni was found to be reversible. The kinetic simulation of the passivation process suggests surface kinetics of adatom species on the timescale of a few seconds.