By use of a crossed free-jet/electron beam technique, an electronic spectrum of dimethylzine cation centered at 608 nm has been discovered, Identification of Zn(CH3)(2)(+) as the carrier of the spectrum is based on comparison with the photoelectron spectrum and rotational-energy-cooling experiments to rule out fragment species. The spectrum is assigned as the (A) over tilde(2)A(1s)-(X) over tilde(2)A(4s) transition of the molecular ion. Analysis of the spectrum reveals a strong origin band system consisting of several sequence bands separated by 51 cm(-1) and a weak progression involving the symmetric methyl deformation vibrational mode, v(2). The term energy of the (2)A(1s) state is determined to be 2.039 eV, and the wavenumber of the v(2) vibrational mode for the ground state is 1086 cm(-1). Unusual intensities and band spacing in the progression are possibly explained by a Fermi resonance. The features found in the spectrum point to a large change in geometry upon ion formation but to similar geometries for the ground and first excited electronic states of the ion presumably because of similar bonding characteristics of the two orbitals involved in this transition. A tentative assignment of another band observed as the (A) over tilde 2E(1d)-(A) over tilde(2)A(1s) transition gives an estimate of the term energy of the (D) over tilde(2)E(1d) state of 4.0 eV.