A kinetic model for the oxidation of organics in water by the combination of hydrogen peroxide and UV radiation is described. The model is based on literature values for a series of reactions initiated by the photolysis of hydrogen peroxide by UV radiation into hydroxyl radicals, to which is added a term for the direct photolysis of the organic. The model is tested with data on the oxidation of a compound, 1,2-dibromo-3-chloropropane (DBCP), at low levels (<500 mu g/L) in simulated and actual groundwater. The effect of the UV intensity, the initial concentration of hydrogen peroxide, and the various inorganic salts is investigated. Nitrate and bicarbonate/carbonate have a detrimental effect on the rate of oxidation of DBCP, the former due to UV shielding and the latter due to (OH)-O-. scavenging. The rate of oxidation of DBCP is enhanced and the optimum peroxide level is lowered at low carbonate alkalinity, suggesting that presoftening of groundwater prior to oxidation of halogenated alkanes should be cost-effective.