  The centre of the Milky Way is the site of several high-energy processes that
have strongly impacted the inner regions of our Galaxy. Activity from the
super-massive black hole, Sgr A*, and/or stellar feedback from the inner
molecular ring expel matter and energy from the disc in the form of a galactic
wind. Multiphase gas has been observed within this outflow, from hot
highly-ionized, to warm ionized and cool atomic gas. To date, however, there
has been no evidence of the cold and dense molecular phase. Here we report the
first detection of molecular gas outflowing from the centre of our Galaxy. This
cold material is associated with atomic hydrogen clouds travelling in the
nuclear wind. The morphology and the kinematics of the molecular gas, resolved
on ~1 pc scale, indicate that these clouds are mixing with the warmer medium
and are possibly being disrupted. The data also suggest that the mass of
molecular gas driven out is not negligible and could impact the rate of star
formation in the central regions. The presence of this cold, dense,
high-velocity gas is puzzling, as neither Sgr A* at its current level of
activity, nor star formation in the inner Galaxy seem viable sources for this
material.
