The electronic structures of formic acid (HCOOH) and formate (HCOO鈥?/sup>) have been determined in aqueous solutions over a pH range of 1.88鈥?.87 using a combination of X-ray photoelectron spectroscopy (XPS), partial electron-yield X-ray absorption spectroscopy (PEY XAS), and density functional theory (DFT). The carbon 1s XPS measurements reveal a binding energy shift of 鈭?.3 eV for deprotonated HCOO鈥?/sup> compared with neutral HCOOH. Such distinction between neutral HCOOH and deprotonated HCOO鈥?/sup> cannot be made based solely on the respective carbon K-edge PEY XA spectra. Independent of pH, the C1s 鈫?蟺* state excitations occur at 288.0 eV and may lead to the incorrect conclusion that the energy levels of the 蟺* state are the same for both species. The DFT calculations are consistent with the experimental observations and show a shift to higher energy for both the occupied C1s (lower binding energy) and unoccupied 蟺* orbitals of deprotonated HCOO鈥?/sup> compared to neutral HCOOH in aqueous solutions.