Reactions of polyatomic organic radicals with gas phase ions have been studied at thermal energy using a flowing afterglow-selected ion flow tube (FA-SIFT) instrument. A supersonic pyrolysis nozzle produces allyl radical (CH2CHCH2) and ortho-benzyne diradical (o-C6H4) for reaction with ions. We have observed: [CH2CHCH2+H3O+-->C3H6++H2O], [CH2CHCH2+HO--->no ion products], [o-C6H4+H3O+-->C6H5++H2O], and [o-C6H4+HO--->C6H3-+H2O]. The proton transfer reactions with H3O+ occur at nearly every collision (k(II)congruent to10(-9) cm(3) s(-1)). The exothermic proton abstraction for o-C6H4+HO- is unexpectedly slow (k(II)congruent to10(-10) cm(3) s(-1)). This has been rationalized by competing associative detachment: o-C6H4+HO--->C6H5O+e(-). The allyl+HO- reaction proceeds presumably via similar detachment pathways. (C) 2004 American Institute of Physics.