  We study the production of two electro-weak vector bosons in association with
a jet via gluon fusion. In particular we consider the production of $\gamma
Zg$, $ZZg$ and $W^{+}W^{-}g$ at hadron colliders and compute their
cross-sections. Such processes have already produced large number of events at
the Large Hadron Collider (LHC) by now. These processes can be background to
the Higgs boson production and a number of beyond the standard model scenarios.
Therefore it is important to know the values of their contribution. The
calculation is based on conventional Feynman diagram approach. In particular we
find that the process $g g \to Z Z g$ can make a significant contribution to
the process $p p \to Z Z + {\rm jet}$.
