Oxidation of guaiazulene (1) with a 2.5 molar amount of m-chloroperbenzoic acid in ethanol at 0 degrees C for 1 h under aerobic conditions gives a ca. 2:1:1 mixture of meso and two enantiomeric forms of 5,5'-biguaiazulene-3,3'(5H,5'N)-dione (2), which upon recrystallization from dichloromethane-hexane selectively provides the single crystals of its meso form only. The first X-ray crystallographic analysis and the electrochemical behavior on the title meso form are reported.