The kinetics and products of the Cl atom initiated oxidation of CH2ClCHClCH2Cl (1,2,3-trichloropropane) have been investigated at (295 +/- 2) K in 700-760 Torr of air in a 405 L reaction chamber. The major oxidation product tin terms of carbon balance) was CH2ClC(O)CH2C1 with smaller amounts of HC(O)Cl and CH2ClC(O)Cl. It was observed that chemical activation effects play a significant role in the atmospheric fate of CH2ClCHClO(.) and CH2ClCO(. )ClCH2Cl radicals. Relative rate techniques were used to measure the following: k(Cl + CH2ClCHClCH2Cl) = (1.86 +/- 0.32) x 10(-12), k(Cl + CHCl = CHCH2Cl) = (1.67 +/- 0.18) x 10(-10), k(Cl + CH(2)double bond CClCH2Cl) = (1.46 +/- 0.15) x 10(-10), and k(Cl + CH2ClC(O)CH2Cl) = (5.53 +/- 0.63) x 10(-13) cm(3) molecule(-1) s(-1). The UV-visible spectrum of CH2ClC(O)CH2Cl was measured over the range 270-385 nm and has a maximum at 305 nm where sigma = (1.6 +/- 0.2) x 10(-19) cm(2) molecule(-1) (base e). Assuming a photolysis quantum yield of 1.00-0.04, the lifetime of CH2ClC(O)CH2Cl with respect to photolysis on a summer day at 40 degrees latitude is calculated to be 0.5 - 12 h. Photolysis is likely to be the dominant atmospheric loss mechanism of CH2ClC(O)CH2Cl. The results are discussed in the context of the atmospheric chemistry of 1,2,3-trichloropropane.