  We have investigated the upper bound of the radiation energy in the head-on
collision of two Myers-Perry black holes. Initially, the two black holes are
far away from each other, and they become one black hole after the collision.
We have obtained the upper bound of the radiation energy thermodynamically
allowed in the process. The upper bound of the radiation energy is obtained in
general dimensions. The radiation bound depends on the alignments of rotating
axes for a given initial condition due to spin-spin interaction. We have found
that the collision may not be occurred for a initially ultra-spinning black
hole.
