CCAST, World Lab, Beijing 100080, Peoples R China
; Inst High Energy Phys, Beijing 100049, Peoples R China
; Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
Motivated by the recent measurement on the upper limit of B-0 -> J/psi D branching ratio, we investigate the B-0 -> J/psi D-(star) and eta D-c((star)) decays in the framework of k(T) factorization. We find that these pure annihilation (W-exchange) decays possess branching ratios of the order 10(-5)similar to 10(-7), which are just at the corner of being observable at the current running B factories. The measurements of these decay channels may help us to understand the QCD dynamics in the corresponding energy scale, and, especially, the distribution amplitudes of charmonium.