  We report the detection of the (1,1) and (2,2) metastable lines of ammonia
(NH_3) in the molecular cloud associated with the Wolf--Rayet (WR) nebula NGC
2359. Besides the CO and H_2, this is the first molecule detected in the
environs of a WR star. Width (3 km/s) and radial velocity (54 km/s) indicate
that the NH$_3$ lines arises from the molecular cloud which is interacting with
the WR star. The rotational temperature derived from the (1,1) and (2,2) line
intensity ratios is about 30 K, significantly larger than the typical kinetic
temperature of the ambient gas of 10 K. The derived NH_3 abundance is 10^{-8}.
Linewidth, abundance and kinetic temperature can be explained if NH_3 is
released from dust grain mantles to the gas phase by shocks produced by the
expansion of the bubble created by the WR stellar wind. We briefly discuss the
implications of the detection of warm NH_3 associated with a WR star in
connection to the hot NH_3 emission detected in the Galactic Center and in the
nuclei of external galaxies.
