The H3N⋯CuCl monomer has been generated and isolated in the gas phase through laser vaporisation of a copper sample in the presence of low concentrations of NH3 and CCl4 in argon. The resulting complex cools to a rotational temperature approaching 2 K during supersonic expansion of the gas sample and is characterised by broadband rotational spectroscopy between 7 and 18.5 GHz. The spectra of six isotopologues are measured and analysed to determine rotational, B0; centrifugal distortion, DJ, DJK; and nuclear quadrupole coupling constants of Cu, Cl, and (14)N nuclei, χaa (X). The geometry of the complex is C3v with the N, Cu, and Cl atoms located on the a inertial axis. Bond distances and the ∠(H -N⋯Cu) bond angle within the complex are precisely evaluated through fitting of geometrical parameters to the experimentally determined moments of inertia and through ab initio calculations at the CCSD(T)(F12*)/AVQZ level. The r(Cu -Cl), r(Cu -N), and ∠(H -N⋯Cu) parameters are, respectively, evaluated to be 2.0614(7) Å, 1.9182(13) Å, and 111.40(6)° in the r0 geometry, in good agreement with the ab initio calculations. Geometrical parameters evaluated for the isolated complex are compared with those established crystallographically for a solid-state sample of [Cu(NH3)Cl].