Valence band structure and electronic parameters of constituent element core levels of RbTiOPO 4 have been analyzed with X-ray photoemission spectroscopy. Detailed photoemission spectra of the element core levels have been recorded under excitation by nonmonochromatic Al KĮ radiation (1486.6 eV). The Ti-O and P-O chemical bonding in RbTiOPO 4 have been considered using binding energy difference parameters and compared with those earlier reported for complex titanates and phosphates.