  We compute the next-to-leading order QCD corrections to the spin-independent
and spin-dependent cross-sections for the production of a single-hadron
accompanied by an opposite jet in hadronic collisions.
  This process is being studied experimentally at RHIC, providing a new tool to
unveil the polarized gluon distribution Delta g. We perform a detailed analysis
of the phenomenological impact of the observable at NLO accuracy and show that
the preliminary data by the STAR collaboration confirms the idea of a small
gluon polarization in the 0.05<x<0.3 range.
