High optical quality crystals of strontium tetraborate SrB4O7 (SBO) have been grown by the Kyropoulos method. The structure of SBO has also been determined. The FWHM of the X-ray rocking curve on the (0 2 1) plane was 0.005degrees. The optical and nonlinear optical properties of the SBO crystal were investigated. The absorption edge in the vacuum UV spectra of the SBO was below 120 rim. Some SHG effects were also investigated. (C) 2002 Elsevier Science B.V. All rights reserved.