We report on the phase-matching properties of borate crystals of LiB₃O₅ (LBO), CsB₃O₅ (CBO), and CsLiB₆O₁₀ (CLBO) in vacuum–ultraviolet (VUV) light generation at around 190 nm. A new phase-matching property in the VUV spectral range for CBO grown from a self-flux solution was found to have better agreement with new Sellmeier's equations developed in our laboratory. A 189 nm output of 11.4 mW was produced in a CLBO with a conversion efficiency of 7.3% from 213 nm input and the generation efficiency from the source laser was 1.6%. CLBO is suitable for VUV light generation around 190 nm with the present laser system.