The photoelectron spectra of PdC2H- and PdC2HN- are presented and analyzed. The electron affinity of the PdC2H complex is 1.98 +/- 0.03 eV, and the electron affinity of the PdC2HN complex is 2.17 +/- 0.03 eV. Both spectra are broadened by unresolved progressions in low-frequency vibrational modes of the neutral. Both also show activation of a higher-frequency mode (1720 +/- 170 cm(-1) for PdC2H and 1800 +/- 200 cm(-1) for PdC2HN) which suggests that back donation from the Pd d(pi) orbitals into the pi* orbitals of the ligands is involved in the bonding in these species. The spectrum of PdC2H- also shows a transition to a dissociative excited neutral state with an excitation energy of 0.35 +/- 0.15 eV. The electronic structures of PdC2H and PdC2H- are explored by comparison with the isoelectronic PdCN and PdCN- species along with supporting density functional theory calculations. (1)Sigma(+), (2)Sigma(+), and (2)Pi terms are proposed for the ground anion, ground neutral, and dissociative neutral states, respectively. A chainlike (nonlinear) Pd-C-C-NH structure is proposed as being consistent with the spectrum of PdC2HN-.