  Here we study the rare decay of $B_c$ mesons within the effective field
theoretical framework of covariant confined quark model. The transition form
factors corresponding to $B_c^+ \to D^{(*)+}$ and $B_c^+ \to D_s^{(*)+}$ are
computed in the entire $q^2$ range. Using form factors we compute the branching
fractions and compare with the available theoretical approaches. We also
compute other physical observables such as forward backward asymmetry,
longitudinal and transverse polarizations and various clean angular
observables.
