A previous theoretical investigation of the multimode dynamical Jahn-Teller effect in the methoxy radical is extended to calculate the vibrational structure of the first bands of the photoelectron spectra of CH3O- and CD3O- and to include the effects of spin-orbit coupling. Bilinear coupling terms between the e and a, vibrational modes are shown to be of major importance for the spectral intensities; they also lead to a marked dependence of the spin-orbit splittings on the quantum numbers of the a, modes in the electronic ground state of the radical. (C) 2003 Elsevier Science B.V. All rights reserved.