In this study, Taguchi method was used to determine optimum conditions for the dissolution of ulexite in perchloric acid slutions. For optimization process; solid-to-liquid ratio, reaction time, particle size and acid concentration were chosen as parameters. In the experiment, stirring speed and reaction temperature were kept as constant. The ranges of experimental parameters-were between 0.1-0.2 g/cm(3) for solid-to-liquid ratio, 1.5-2.5 M for acid concentration, 165.0-512.5 mu m for particle size and 12-36 min for reaction time. In the end of the experimental sections the optimum conditions were determined as 0.1 g/mL for solid to liquid ratio; 215 mu m for particle size; 24 min for reaction time; 500 rpm for stirring speed; 30 degrees C for reaction temperature and 2 mol/dm(3) for acid concentration. Under these conditions, it was found that the boric acid extraction from ulexite was reached a value of 99 %.