  The decay process $B\to D^+ D^- \pi^0$ is an interesting channel for the
investigation of CP violating effects in the $b-$ sector. We write down a decay
amplitude constrained by a low-energy theorem, which also includes the
contribution of resonant $S-$ and $P-$wave beauty and charmed mesons, and we
determine the relevant matrix elements in the infinite heavy quark mass limit,
assuming the factorization ansatz. We estimate the rate of the decay: ${\cal
B}(B \to D^+ D^- \pi^0)\simeq 1 \times 10^{-3}$. We also analyze the
time-independent and time-dependent differential decay distributions,
concluding that a signal for this process should be observed at the
B-factories. Finally, we give an estimate of the decay rate of the
Cabibbo-favoured process $B\to D^+ D^- K_S$.
