Hydrolysis of Cr2O7-2 ion in the presence of TRIS buffer (H2NC(CH2OH)3. pH 7.55-8.96) involves nucleophilic catalysis (k1 = 55 M-1 s-1, 25-degrees-C, I = 1.0 M NaClO4) with the intermediate (TRIS)CrO3 species (H3N+C(CH2OH)2CH2OCrO3-, pK(a)c = 8.00) decaying to free TRIS and CrO42- via TRIS general base (k2 = 6.4 M-1 s-1) and specific OH- (k(OH) = 2.2 x 10(4) M-1 s-1) catalyzed pathways. Rate constants for the catalyzed hydrolysis of Cr2O72- by eight other species of basicity comparable (+/- 2 pK units) with TRIS (TRISH+, pK(a) = 8.12) vary by factors of up to 10(5).