The recent success in the formation of chlorinated telluraboranes and the reactivities of pnictogenaboranes prompted us to re-examine the vacuum co-pyrolysis of B(2)Cl(4) with Se(2)Cl(2) at various molar ratios and temperatures in order to search for the generation of other polyhedral selenaboranes than closo-SeB(5)Cl(5) (1a) and closo-SeB(11)Cl(11) (1b), the latter being observed earlier. Interestingly, a new compound with the elemental composition SeB(9)Cl(9) (2) was detected, this time …