Above pH 5, the hydrolysis of 6-trichloromethylpurine (HPuCCh) to purinoic and hydrochloric acids in dilute, aqueous solutions proceeds as follows. (1) HPuCCh is ionized to (PuCCl3), the relative concentration of which depends on the pH and the pKa of HPuCCh. (2) (PuCCh)- loses Cl~ in a rate-determining step, yielding a reactive intermediate, Pu=CCk. (3) The latter is sufficiently stable to discriminate between various nucleophiles, its relative reaction rates with water, Cl~, or OH~ being 1, 233, and 1290, respectively. Non-ionized HPuCCh is capable of undergoing hydrolysis, but at a rate much slower than (PuCCl3)~, the first-order rate constants being 8 X 10~7 and 1.09 X 10~3 sec1, respectively. The relative stability of the CCl3 group in HPuCC3, compared to structurally related systems, is ascribed to the double bond-no bond resonance of the molecule.