In acidic solutions 1,3,5-tripyrrolidinobenzene (TPB) and methyl-TPB hydrolyse forming 3,5-dipyrrolidinophenol (DPP) and methyl-DPP, respectively. The reaction proceeds by two successive protonations on carbon atoms of the aromatic ring followed by hydrolysis. The reaction mechanism is described, and the protonation equilibria of TPB and DPP are determined.