We　report　results　of　X-ray　diffraction　(XRD)　and　valence　band　X-ray　photoelectron　(VB-XPS)　spectra　for　strontium　borate　Sr2B16O26.　The　X-ray　structural　analysis　shows　that　the　single　crystals　of　Sr2B16O26　crystallize　in　the　monoclinic　space　group　P2(1)lc　with　a　=　8.408(1)　angstrom,　b　=　16.672(1)　angstrom,　c　=　13.901(2)　angstrom,　beta　=　106.33(　1)degrees,　and　Z　=　4.　The　crystal　structure　consists　of　a　3D　network　of　the　complex　borate　anion　[B16O20O12/2](4-),　formed　by　12　BO3　triangles　and　four　BO4　tetrahedra,　which　can　be　viewed　as　three　linked　[B3O3O4/2](-)　triborate　groups　bonded　to　one　pentaborate　[B5O6O4/2](-)　group　and　two　BO3　triangles.　Using　this　structure,　we　have　performed　theoretical　calculations　using　the　all-electron　full　potential　linearized　augmented　plane　wave　(FP-LAPW)　method　for　the　hand　Structure,　density　of　states,　electron　charge　density,　and　the　frequency-dependent　optical　properties.　Our　experimental　VB-XPS　of　Sr2B16O26　is　compared　with　results　of　our　FP-LAPW　calculations.　Our　calculations　show　that　the　valence　hand　maximum　(VBM)　and　conduction　hand　minimum　(CBM)　are　located　at　Gamma　of　the　Brillouin　zone　(BZ)　resulting　in　a　direct　energy　gap　of　about　5.31　eV.　Our　measured　VB-XPS　show　reasonable　agreement　with　Our　calculated　total　density　of　states　for　the　valence　band　that　is　attributed　to　the　use　of　the　full　potential　method.