The constitution of the cyclooctatetraene tetramer, mp 182° (VI), is derived from its spectroscopic properties and from the results of catalytic hydrogenation experiments. The 1H‐NMR spectrum of VI is temperature dependent and indicates the presence of two homotropylidene residues in the molecule, one isomerizing isodynamically, the other anisodynamically. The mass spectrum of VI shows remarkable similarities with those of the cyclooctatetraene dimer, mp 76° (III) and of bullvalene (IX). The tetramer VI is concluded to be the product of a 2 + 4‐cycloaddition reaction between the cyclohexa‐1,3‐diene units of two molecules of III. The tetramer VI appears to be configurationally unique. This is explained and a configuration is proposed on the basis of the stereospecificity of the reaction leading to VI.