Ozonation membrane contact was carried out with a tubular membrane module to study the effects of the flow rates and the temperatures of the liquid phase on ozone transfer and on the enhancement of mass fluxes. Changes in liquid temperature gave both positive and negative effects on the ozone fluxes for the nitrite solutions. The increase of the ozone fluxes with temperature was observed until the temperature approached approximately 40 degrees C. Ozonation membrane contact was also applied to decolorize Norwegian natural organic matter (NOM) at typical color concentrations in the range of 15-20 mg Pt/L. The ozone consumption for NOM decolourization tended to decrease with the liquid flow rates. A simple mass transfer model was proposed for the ozonation membrane contactor for the NOM decolourization studied here. The model was developed based on the concepts of the ozone consumption and the enhancement factor and can be used to describe the influence of mass transfer on the effluent colour concentration of the NOM. The experimental results validated the proposed model with deviations in the range of -9 to + 7%. The decolourization rate constants obtained from the concentration-time (C-tau) model for the ozonation membrane contactor were found to be in the range of 139.44-298.81 M-1 s(-1). Simple concept to design ozonation membrane contactor for NOM decolourization was proposed. The kinetic characteristics for the NOM decolourization in ozonation membrane contactor are discussed in this paper. (c) 2005 Elsevier B.V. All rights reserved.