The yield, Y, the spin-orbit branching ratio, Gamma, and the angular anisotropy, beta(2), of Cl atoms produced by predissociation of the E (1) Sigma(+) and g (3) Sigma(0)(-) Rydberg states of HCl and DCl are reported as functions of the rotational angular momentum J. For the E state, Y increases with J for HCl and decreases with J for DCl, whereas Gamma and beta(2) are independent of J for both isotopomers. For the g(0) state Y increases with J, whereas Gamma and beta(2) both decrease with J for both isotopomers. The different dynamical behavior of these two O+-symmetry states belonging to the same zero-order electronic configuration is explained in terms of their diabatic characters.