The discrete vapor phase absorption spectrum of oxalyl bromide in the 4400-3200 Å regions has been analyzed into two systems. The S- S system is rotationally diffuse throughout, while bands of the much weaker T- S system are relatively sharp near the origin. Both systems show increasing diffuseness to higher frequencies. The electronic origins are at 25 371 cm −1 ( S- S) and 22 938 cm −1 ( T- S). Both systems show a similar vibrational structure, and are also similar to their counterparts in oxalyl chloride. They are analyzed as electronically allowed transitions (with the T- S system spin forbidden) between planar, trans, states of the molecule. Upper state frequencies ν 1′ - ν 5′ are respectively; 1538, 953, 621, 296, and 180 cm −1 ( S- S); 1537, 1003, 642, 312, and 186 cm −1 ( T- S). Sequence intervals of (+32)cm −1 ( ν 6 sequence) and (+65)cm −1 ( ν 7 sequence) are prominent in both spectra, and the lower state fundamental frequencies agree with values obtained from the infrared and Raman spectra. Both transitions result from the same n → π ∗ electron promotion in the molecule, the transitions being A ̃ 1A u ← X ̃ 1A g for the S- S and a ̃ 3A a ← X ̃ 1A g for the T- S systems, respectively.