We　have　synthesized　and　characterized　the　bismuth　borate　Bi2ZnB2O7　single　crystals.　The　results　of　the　experimental　measurements　of　the　X-ray　diffraction　(XRD)　and　X-ray　photoelectron　spectrum　(XPS)　along　with　an　ab　initio　theoretical　study　of　the　electronic　band　structure,　and　density　of　states,　are　reported.　The　theoretical　calculations　are　based　on　crystal　structure　built　from　our　experimentally　determined　atomic　parameters.　The　theoretical　calculations　have　been　done　by　using　the　full　potential　linearized　augmented　plane　wave　(FP-LAPW)　method.　We　applied　the　Perdew-Burke-Ernzerhof　generalized　gradient　approximation　(GGA)　and　the　Engel-Vosko　GGA　formalism.　The　observed　XPS　pattern　is　in　good　agreement　with　the　theoretical　one,　confirming　the　pure　phase　of　Bi2ZnB2O7.　The　purity　and　composition　of　the　as-prepared　sample　are　studied　by　XPS　analysis.　XPS　measurements　show　that　the　bismuth　possesses　+3　valence　state,　and　Zn　and　B　species　exist　only　in　the　traditional　valence　states　of　Zn2+　and　B3+.　The　O　1s　spectra　are　broad　and　asymmetric　and　can　be　deconvoluted　into　two　peaks.　The　lower　and　higher　binding　energy　peaks　(around　530.1　and　531.5　eV)　are　assigned　to　originate　from　O　1s(1)　and　O　1　s(2)　terms,　respectively,　which　are　attributed　to　non-bridging　oxygen　(B-O-　bonds)　and　bridging　oxygen　(B-O-B　bonds),　respectively.　Our　calculations　show　that　Bi2ZnB2O7　has　an　indirect　energy　gap　and　that　Bi-O　bonds　are　of　strong　covalent　character.　(C)　2008　Elsevier　Ltd.　All　rights　reserved.