The experimental photoelectron spectrum of Ga2P2- reported by Taylor, Asmis, Xu and Neumark [Chem. Phys. Lett. 297 (1998) 133] is interpreted using quantum chemical calculations. The anion has a C-2v distorted tetrahedron structure and the neutral has a D-2h rhombic structure. Vertical electron detachment energies (VEDE) From the B-2(1) ground electronic state of Ga2P2- to various electronic states of Ga2P2 are presented, discussed and correlated with the experimental results. Harmonic vibrational frequencies and adiabatic electron detachment energies (AEDE) are also reported to aid future assignment of the vibrationally resolved spectrum of the Ga2P2-/Ga2P2 system.