A series of new bis-benzocyclobutene-endcapped arylene ether monomers was prepared and characterized. Whereas 2,6-bis(4-benzocyclobutenyloxy)benzonitrile (BCB-EBN) could be prepared in good yield using the standard procedure (K2CO3/NMP/toluene/Dean-Stark trap/120 degrees C), other bis(benzocyclobutene) (BCB)-terminated monomers containing ether-benzophenone (BCB-EK), ether-phenylsulfone (BCB-ES), and ether-6F-benzoxazole (BCB-EBO) moieties were invariably contaminated by mono-endcapped products under similar reaction conditions. This can be attributed to a much greater activating effect of the nitrile group on the ortho-fluorides in the aromatic nucleophilic displacement reaction than the carbonyl, sulfonyl, and benzoxazolyl groups. However, the latter monomers could be synthesized (70-80%) from 4-trimethylsiloxybenzocyclobutene and respective aromatic fluorides in the presence of CsF at 140 degrees C. Similar curing behaviors under N-2 (DSC : extrapolated onset and peak temperatures at 227-230 degrees and 260-262 degrees C, respectively) characterized all four monomers. BCB-EK, BCB-ES, and BCB-EBN showed melting transitions at 108, 119, and 146 degrees C, in that order. As BCB-EBO contained more rigid benzoxazole segments, it only exhibited a glass transition (T-g) at 85 degrees C prior to curing exotherm, after it had been previously heated to 125 degrees C. The following T(g)s were observed for the cured materials : BCB-EK (201 degrees C), BCB-EBN (224 degrees C), BCB-ES (264 degrees C), and BCB-EBO (282 degrees C). The relative thermal stability according to TGA (He) results is : BCB-ES < BCB-EBN < BCB-EK < BCB-EBO. Finally, the results from thermal analysis, infrared spectroscopic, and variable temperature microscopic studies indicated that the nitrile group plays an important role in the cure chemistry, thermal, and microstructural properties of BCB-EBN.