Rate coefficients for the reaction of OH radical with HCl (k(1)) between 200 and 400 K, were measured to be 3.28 x 10(-17) T-1.66 exp [184/T] cm(3) molecule(-1) s(-1) by producing OH via pulsed laser photolysis and detecting it via laser induced fluorescence. The rate coefficients for the reactions of OH with DCl (k(2)), OD with HCl (k(3)), and OD with DCl (k(4)) were also measured using the same method to be k(2) = 2.9 x 10(-12) exp [-728/T], k(3) = 8.1 x 10(-18) T-1.85 exp [300/T], and k(4) = 2.5 x 10(-12) exp [-660/T] cm(3) molecule(-1) s(-1). k(1) - k(4) were computed for 200 < T < 400 K using the variational transition theory, including tunneling corrections, to be k(1) = 1.49 x 10(-16) T-1.35 exp [262/T], k(2) = 9.04 x 10(-20) T-2.34 exp [429/T], k(3) = 1.01 x 10(-16) T-1.4 exp[309/T], and k(4) = 1.64 x 10(-19) T-2.27 exp [385/T]cm(3) molecule(-1) s(-1), in reasonable agreement with experiments. They were also used to analyze the origin of the isotope effects. A two-dimensional chemical transport model calculation shows that our measured higher values of k(1) at low temperatures do not significantly alter the calculated ozone abundance, or its trend, in the stratosphere.