Differential cross-section for both the channels of the reaction He + HD+ (v = 0, 1, 2,3; j = 0) HeH(D)(+) + D(H) has been calculated using the time-dependent quantum mechanical methodology (helicity basis truncated at k 2) on the Palmieri et al. potential energy surface at relative translational energy E-trans= 1.0 eV. It is shown that HeH+ would be formed preferentially over HeD+ in the forward direction, while HeD+ would be preferred over HeH+ in the backward direction for v = 1, 2, 3. For v = 0, HeH+ is scattered preferentially over HeD+ in all directions. Therefore, the isotopic branching ratio and its dependence on product scattering angle can be a sensitive probe of the potential energy surface. (c) 2005 Elsevier B.V. All rights reserved.