The decontamination of prometon (PMT) by ozone/hydroxylamine hydrochloride (O-3/HAC) was systematically investigated in this study with focus on the degradation mechanism and kinetics. Experimental results revealed that there was an enhancement of PMT degradation efficiency by 42.1% and the pseudo-first-order rate constant by more than 5.7 times in O-3/HAC process under low HAC dosage (5 mg L-1) after 3 min in comparison with O-3 alone. The second-order rate constant of PMT with hydroxyl radical ((OH)-O-center dot) was determined to be (1.84 +/- 0.1) x 10(9) M-1 s(-1) and 7.80 x 10(9) M-1 s(-1) via competition kinetics and (OH)-O-center dot steady-state hypothesis, respectively. The PMT removal in 0 3 /HAC process was highly pH-dependent and the optimum degradation performance was achieved under pH 5.0. In addition, (OH)-O-center dot and singlet oxygen were identified as the primary reactive oxygen radicals in O-3/HAC process. Meanwhile, eleven transformation products of PMT were identified and possible degradation mechanisms were proposed. Moreover, a kinetic model based on chemical kinetics and steady-state hypothesis was developed and modified to predict the PMT abatement in O-3/HAC process. The results demonstrated that the O-3/HAC process provided a promising alternative for refractory organic pollutants decontamination in water treatment.