Emission spectra of glyoxal, glyoxal-d1, and glyoxal-d2 have been excited using the various lines of an argon ion laser. The bands have been assigned to 3 band systems, viz. the 1Au–1Ag and 3Au–1Ag (π*–n) systems of the trans molecule and the 1B1–1A1 (π*–n) system of the cis molecule. The vibrational constants are in good agreement with earlier values. Some new vibrational constants have been determined.