Triarylpropargyl cations have hitherto been successfully prepared only by the introduction of strong electrondonating substituents. Molecular design that does not rely solely on strong electron-donating groups is required, which would not only allow for accurate elucidation of the electronic properties but also pave the way for further developments in the chemistry of propargyl cations. The major degradation processes of propargyl cations involve nucleophilic attack on the C3 atom corresponding to the cationic centre of the allenyl cation form, and subsequent tautomerization into thermo-dynamically stable vinyl ketone derivatives. Thus, by sterically protecting the C3 position, we conceived that stable triarylpropargyl cations could be made without strong electron-donating groups, and newly designed triarylpropargyl cations 1 + ,2 + : mesitylethynyl-substituted bis(4methoxyphenyl)methyl cation and xanthenyl cation.