The gaseous MgH2 molecule has been discovered in an electrical discharge inside a high temperature furnace. The vibration-rotation emission spectrum of (MgH2)-Mg-24 was recorded with a Fourier transform spectrometer and the antisymmetric stretching mode (nu(3)) was detected near 1589 cm(-1). In addition, three hot bands involving nu(2) and nu(3) were found and rotationally analyzed. The MgH2 molecule has a linear structure with an R-0 Mg-H bond distance of 1.703 327(3) Angstrom. (C) 2003 American Institute of Physics.