  We study scalar perturbations of the five-dimensional rotating black holes
and find an exact solution giving exact description of the Hawking radiation.
Mathematically, the full solution for this s-wave mode is expressed in terms of
the prolate spheroidal wave function with complex parameters. By using the
spheroidal joining factor, we write the corresponding boundary condition and
greybody factors. We also check that the exact result reproduces the low
frequency limit of the greybody factor and shows good agreement with the known
numerical results.
