Potassium lithium tantalate niobate, K3Li2(TaxNb1-x)5O15, or KLTN single crystals were grown by spontaneous crystallization method, and it has been demonstrated that the KLTN crystal has high potential as a nonlinear crystal for blue second‐harmonic‐generation (SHG) applications. Ta substitution for Nb site in K3Li2Nb5O15 crystal improves the transparency in the blue light region and decolorizes the material. Compared with K3Li2Nb5O15, the K3Li2Ta5O15 crystal exhibits a 60 nm blueshift of the absorption edge from 376 to 316 nm, and decreases its absorption coefficient from 2.3 to 0.3 cm-1 at 400 nm. The phase‐matched frequency doubling of the Ti:sapphire infrared laser for blue SHG at room temperature has been demonstrated with the KLTN bulk crystal. © 1996 American Institute of Physics.