  We discuss the ${\cal O}(\alpha_s)$ supersymmetric QCD corrections to
neutralino-stop coannihilation into a top quark and a gluon in the Minimal
Supersymmetric Standard Model (MSSM). This particular channel can be
numerically important in wide ranges of the MSSM parameter space with rather
light stops. We discuss technical details such as the renormalization scheme
and the phase-space slicing method with two cutoffs. We also comment on
improvements with respect to earlier works on the given process. Further, we
study for the first time the phenomenologically very interesting interplay of
neutralino-stop coannihilation with neutralino-pair annihilation into quark
pairs taking the full next-to-leading order SUSY-QCD corrections into account.
We demonstrate that the numerical impact of these corrections on the total
(co)annihilation cross section and finally on the theoretically predicted
neutralino relic density is significant.
