If this was when he was under ghetsis's control, then no. When you fight ghetsis and kyurem in giant chasm, ghetsis controls kyurem with a staff that prevents it from being captured in pokeballs. Since you only see "wild" black kyurem when ghetsis controls him with this staff in the battle in the giant chasm, it is impossible to catch black kyurem. However later in the game you can catch regular kyurem, and after that N will give you the oppurtunity to catch his zekrom. If you catch both of them, you may combine them into black kyurem using the DNA splicers at your leisure.
