Equilibrium geometries, harmonic vibrational frequencies and electron detachment energies are reported for AlP2- and Al2P2-. The adiabatic electron affinity of AlP2 is calculated to be 1.92 eV at the CCSD(T) level. The (2)A(1) and B-2(1) lowest excited states of AlP2 are located at 0.41 eV and 2.53 eV, respectively, above the B-2(2) ground state. The Al2P2- anion has a distorted tetrahedron geometry (B-2(1)-C-2v) and the adiabatic electron affinity of Al2P2 ((1)A(g)-D-2h) is computed to be 1.83 eV at the CCSD(T) level. Electron detachment processes from the B-2(1)-C-2v ground state of Al2P2- to neutral states of Al2P2 are presented and discussed.