The photooxidation of allyl chloride was studied by irradiation either in 100-L Teflon bags or in a 22.7-cu m Teflon smog chamber in the presence of added NOx. In the absence of added hydrocarbons, the reaction involves a Cl atom chain, which leads to a highly reactive system. A reaction mechanism is presented to account for the following photooxidation products: chloroacetaldehyde, formaldehyde, 1,3-dichloroacetone, 3-chloroacrolein, acrolein, glyoxal, chloroperoxyacetylnitrate, and peroxypropenylnitrate. The rate constant for OH reaction with allyl chloride at 298K was measured by a relative rate method under conditions where the Cl atom chain length was small and was found to be kOH = 1.7 x 10 to the minus 11th power cc molecule (-1) sec (-1). (Copyright (c) John Wiley & Sons, Inc.)