  Within the DWBA framework, we develop a theoretical description of single and
double heavy ion charge exchange (CE) reactions. We show that absorption
effects are particularly important for heavy ion reactions, leading to a
noticeable reduction of the CE cross sections. At low momentum transfer, the
single CE cross section can be factorised, thus allowing to evaluate
corresponding distortion factors and access beta decay strengths. Applications
are shown for a system of experimental interest. Preliminary results are
discussed also for double CE reactions, modeled as a two-step mechanisms, i.e.
a sequence of two charge-changing processes.
