The coherent Raman spectroscopic techniques CARS and PARS have been used to study glyoxal (C2H2O2) in the vapour phase. The following fundamental vibrational frequencies for trans‐glyoxal have been determined: ν1 = 2840 ± 2, ν2 = 1742.5 ± 0.5 and ν3 = 1353.5 ± 0.5 cm−1. Several hot and combination bands have also been identified. The rovibrational contour of the ν2 band is unexpectedly broad and structured and a variety of possible sources of this apparent anomaly are investigated. Novel experimental strategies include simultaneous recording of CARS and PARS spectra, major variations of pump and Stokes wavelengths to eliminate resonantly enhanced processes and rotationally resolved Raman–optical double resonance spectroscopy.