  We describe an effective-theory computation of the next-to-next-to-leading
order (NNLO) QCD corrections to the gluon-fusion production of a Higgs boson in
models with massive color-octet scalars in the (8,1)_0 representation.
Numerical results are presented for both the Tevatron and the LHC. The
estimated theoretical uncertainty is greatly reduced by the inclusion of the
NNLO corrections. Color-octet scalars can increase the Standard Model rate by
more than a factor of two in allowed regions of parameter space.
