We　have　synthesized　and　characterized　single-crystal　of　bismuth　borates　Bi2ZnB2O7.　The　results　of　the　experimental　measurements　and　the　ab　initio　theoretical　study　of　the　linear　and　non-linear　optical　susceptibilities　are　presented　here.　Theoretical　calculations　are　based　on　a　structural　model　built　from　our　measured　atomic　parameters.　The　optical　properties　were　measured　by　analyzing　the　diffuse　reflectance　data　obtained　with　a　Shimadzu　UV-3101　PC　double-beam,　double-monochromator　spectrophotometer.　This　compound　shows　an　absorption　edge　at　about　360　nm　corresponding　to　energy　3.44　eV.　The　theoretical　calculations　have　been　performed　by　using　the　full　potential　linearized　augmented　plane　wave　(FP-LAPW)　method.　We　have　used　the　generalized　gradient　approximation　(GGA),　using　the　exchange-correlation　energy　of　Engel-Vosko.　We　present　calculations　of　the　frequency-dependent　complex　dielectric　function　epsilon(omega)　and　its　zero-frequency　limit　epsilon(l)(0).　The　optical　properties　are　analyzed　and　the　origin　of　some　of　the　spectral　peaks　is　discussed　in　terms　of　the　calculated　electronic　band　energy　structure.　The　linear　optical　properties　show　strong　negative　uniaxial　anisotropy　and　birefringence　which　favors　large　second　order　susceptibility　chi((2))(ijk)(omega).　Our　calculations　show　that　chi((2))(333)(omega)　is　the　dominant　component　possessing　the　largest　total　Re　chi((2))(ijk)(0).　(C)　2008　Elsevier　Ltd.　All　rights　reserved.