1. The triphenylallyl cation, obtained directly in the acid cleavage of 1,2,3-triphenylcyclopropene, was fixed by its quantitative conversion to cis-1,2, 3-triphenyl-1-propene in the presence of a hydride-ion donor, which experimentally confirms the adopted mechanism of the rearrangements in the cyclopropene series under the influence of acids. 2. The opening of the three-membered ring in the studied reaction proceeds stereospecifically, with a disrotator rotation of the substituents on the outside in harmony with the Woodward-Hoffman rule.