Chlorine dioxide delignification (D 0 ) modifies kraft residual lignin by oxidizing phenolic groups to both quinone and muconic acid structures. Alkaline extraction (E), in addition to removing solubilized lignin, converts quinone moieties to polyphenols. These polyphenols are easily oxidized by oxygen in an (EO) stage or by ClO 2 in a D 1 stage to hydroxyquinones (1.8 mmol/g lignin). Pulps treated by D 0 E consume considerably more ClO 2 in the D 1 than D 0 (EO), and have lower bleachability, as was quantified by a simple bleaching model. Both D 0 E and D 0 (EO) pulps approach a common brightness ceiling (83 ISO) when excess ClO 2 is applied. Examination of the post-D 1 b à values indicates that D 0 E and D 0 (EO) also have similar asymptotic b à values (6), indicating that both pulps have similar Dedicated to Drs. Donald R. Dimmel and Thomas J. McDonough on their retirement from the Institute of Paper Science and Technology.