We succeeded in growing the KF-doped BaTiO3 single-crystals by changing the molar ratios of the liquidsolution consisting of KF: BaO: TiO2 = 10: 1: 1+α where is a variable in a range up to 1.2. The content x in the chemical formula, Ba1-xKxTiO3-xFx, was evaluated by using an electron-probe micro-analyzer: x changes continuously to approximately 0.10 as α increases to 1.0. Temperature dependence of the dielectric constant was measured using these crystals with different x. The ferroelectric Curie-temperature TC decreases monotonously from 390 K to 280 K with increasingαfrom 0 to 1.2, while the maximum value of the dielectric constant εmax at TC exhibits a peak around α= 1.0.