In this study, a kinetic model of the final bleaching stage with hydrogen peroxide in a totally chlorine free (TCF) bleaching sequence for ALCELL(R) processed pulp was developed. The model was based on the rate of chromophore destruction characterized by the decrease in the light absorption coefficient of bleached pulp at 457 nm, C-K. Based on the fact that the chromophore destruction proceeds rapidly in an initial phase followed by a much slower reaction during which a "floor-level" chromophore concentration is approached asymptotically, we propose that the hydrogen peroxide stage of the ALCELL(R) derived pulp in the studied TCF sequence consists of two distinct phases. The initial phase is a very fast reaction. The rate equation of the second phase was determined as : - dC(K)/dt = 1.41 x 10(10) exp(-69610/RT)[HOO-](0.5)[C-K-C-Kf](2) which is valid in a pH range of 10.5 to 11.5 and a temperature range of 60 to 92.5 degrees C.