We have previously reported on the synthesis of a new 2,5-disubstituted benzocyclobutene monomer which is capable of undergoing thermally activated cross-linking. This monomer, a derivative of terephthalic acid, can be incorporated into the backbone of many high-performance polymers, processed into films or fibers, and then cross-linked to yield networks. To determine the operating window for polymerization and processing, we report here a study on small-molecule compounds derived from this monomer, many of which have well-known polymeric counterparts. When electron-withdrawing groups are present on the benzocyclobutene ring, stability toward strong protonic acids is shown to be excellent. This is in contrast to the case of the parent hydrocarbon and derivatives substituted with electron-donating groups and is consistent with acid degradation resulting from electrophilic aromatic substitution chemistry. Thermal analysis of the model compounds by differential scanning calorimetry reveals that exothermic reaction maxima are typically around 350-degrees-C, which is approximately 100-degrees-C higher than the maxima for 3-substituted benzocyclobutene derivatives. When the thermal reaction is performed in the presence of dienophiles, reaction temperatures are lowered by as much as 100-degrees-C. Possible explanations for the thermal reactivity are discussed. No significant correlation to the electronic structure of the cyclobutaarene ring is observed nor is there any significant relationship between reactivity and melting transition. The apparent greater thermal stability for 2,5-disubstituted benzocyclobutenes is most consistent with the encumbered steric environment around the cyclobutaarene ring.