Response surface methodology was used to investigate the main effects and interactions of ozonation on orange juice colour degradation. A Box-Behnken experimental design was employed with control variables of gas flow rate (0-0.25 L min(-1)), ozone concentration (1.2-4.8%w/w) and treatment time (2-10 min). Predicted models were found to be significant (p < 0.001) with regression coefficients of 0.97, 0.97, 0.99, 0.99, 0.99, 0.98 for L*, a*, b*, chroma, TCD, hue, respectively. Predicted values of colour parameters obtained using model equations were in good agreement with the experimental values. Gas flow rate, ozone concentration and treatment time were found to be critical factors influencing colour degradation. This study showed that Box-Behnken design and response surface methodology could be employed to model colour degradation parameters of ozonated orange juice while minimising the number of experiments required. (c) 2008 Elsevier Ltd. All rights reserved.