we present complementary X-ray diffraction, absorption, and emission studies of lanthanum oxycarbonate nanoparticles. To calculate the accurate XAS spectra with FEFF code a precise determination of atomic positions is required. Using the PXRD pattern we determine the atomic structure of monoclinic type Ia La2O2CO3. Eventually, this information is the foundation for the FEFF calculations, which reproduce the measured XAS spectrum very well. Moreover, we experimentally verify that the La d-states are partially occupied and the empty fraction forms the conduction band, the occupied fraction forms together with O p-states the valence bands, and the electronic d-DOS band gap between them is 3.7 eV. To further elucidate the role of the oxycarbonate ligands an advanced density functional theory calculation of XES spectrum is needed (12). Herein the combination of HERFD XAS and vtc XES techniques allows us to in situ visualize the charge transfer between relatively inert carbon dioxide and La2O2CO3. It reveals changes of both occupied (La d and O p) and unoccupied states (La d) upon the