The dynamics of the gas-phase reaction of H atoms with HCl has been studied experimentally employing the laser photolysis/vacuum-UV laser-induced fluorescence (LP/UV-LIF) "pump-and-probe" technique and theoretically by means of quasiclassical trajectory (QCT) calculations performed on two versions of thr new potential energy surface of Bian and Werner [Bian. W.; Werner, H.-J, J. Chem. Phys. 2000, 112,220]. In the experimental studies translationally energetic ii atoms with average collision energies of E-col = 1.4 and 1.7 eV were generated by pulsed laser photolysis of H2S and HBr at 222 nm, respectively. Ground-state Cl(P-2(3/2)) and spin-orbit excited Cl*(P-2(1/2)) atoms produced in the reactive collision of the H atoms with room-temperature HCl were detected under single collision conditions by VUV-LIF, The measurements of the Cl* formation spin-orbit branching ratio phi (Cl)* (1.4 eV) = [Cl*]/[Cl + Cl*] = 0.07 +/- 0.01 and phi (Cl)*(1.7 cV) = 0 19 +/- 0.02 revealed the increasing importance of the nonadiabatic reaction channel H + HCl --> H-2 + Cl* with increasing collision energy. To allow for comparison with the QCT calculations, total absolute rractiun cross sections for chlorine atom formation, sigma (R)(1.4 eV) = (0.35 +/- 0.16) A(2) and sigma (R)(1.7 eV) = (0.13 +/- 0.06) Angstrom (2), have been measured using a photolytic calibration method. In addition, further QCT calculations have been carried out for the H + DCl isotope reaction which can be compared with the results of previous reaction dynamics experiments of Barclay et al. [Barclay, V. J,; Collings, B, A.; Polanyi. J. C.; Wang, J. Ii. J. Phys. Chem. 1991, 95, 2921].