Product studies of Cl atom initiated oxidation of ClCH2CHO and Br atom initiated oxidation of BrCH2CHO were conducted by FTIR spectroscopy at 297 +/- 2 K in 700 Torr of O-2/N-2 diluent, using reactant partial pressures in both the torr and millitorr ranges. The halogen atoms initiate reaction via hydrogen abstraction from the aldehydic group (CHO), producing haloacetyl radicals, XCH(2)CO, where X = Cl or Pr. In 700 Torr of air, the XCH(2)CO radicals may react via three channels : (i) O-2-addition, XCH(2)CO + O-2 --> XCH(2)C(O)O-2; (ii) unimolecular dissociation by C-C bond cleavage, XCH(2)CO (+M) --> XCH(2) + CO (+M); and (iii) unimolecular dissociation by C-X bond cleavage, XCH(2)CO (+M) --> X + CH2C=O (+M). All three channels were observed for BrCH,CO radicals, enabling estimation of the branching ratios, but ClCH2CO reacts only by O-2-addition. Subsequent reactions of XCH(2)C(O)O-2 radicals lead to XCH(2)O radical and CO2 formation. The ClCH2O radical reacts with O-2 to produce CHClO and HO2, while the BrCH2O radical mainly eliminates the Pr atom, based on CH2O detected.