The electronic structure of the low-energy states of pyromellitic diahydride (PMDA) anion is investigated in terms of density functional theory (DFT). The studies are carried out with a use of the local spin density VWN (Vosco-Wilk-Nusair) and the nonlocal spin density BP (Becke-Perdew) models. To explore the role of the diffuse functions located on carbon and oxygene atoms, the B3LYP method was also employed with 6-31+G* and 6-31G* basis sets. At this level of approximation, the Franck-Condon (FC) parameters were evaluated for the nine totally symmetric modes of PMDA anion in its low-energy dipole-allowed 1(2)B(3g) and 1(2)B(1g) states. These parameters are then employed to reconstruct and discuss the vibrational structure of the experimental absorption and RR spectra measured in the region corresponding to the low-energy 1(2)A(u) --> 1(2)B(3g) transition. It is shown that a weak mixing of the CC stretching modes upon excitation to the 1(2)B(3g) state and an inhomogeneous broadening of vibronic transitions have a marked effect on the absorption and resonance Raman spectra.