Summary: Two types of bis(2,5‐diphenyl‐1,3,4‐oxadiazole)s, macrocyclic and acyclic, were prepared and evaluated as electron‐transporting and hole‐blocking materials in phosphorescent EL devices. Maximum efficiencies of ηext = 10.4% at J = 0.11 mA · cm−2 for the macrocycle and ηext = 14.1% at J = 3.01 mA · cm−2 for the acycle were observed. X‐ray crystallographic analysis and DSC measurements revealed a strong intermolecular interaction between the macrocycles and weaker intermolecular interactions between the acycles. The EL characteristics depend on the intermolecular interactions.