The aim of the study was to investigate the optimization of the dissolution of tincal ore in phosphoric acid solutions at high temperatures in a batch reactor. The effect of the following parameters on the dissolution process was investigated: the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The best conditions for the dissolution were determined using the 2(4) factorial experimental design method. The optimum values of the parameters were experimentally determined. The effective parameters were the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The optimum conditions resulted in the maximum boron dissolution at an acid concentration of 1M, reaction temperature of 85 degrees C, particle size of 4.75 mesh, and solid-to-liquid ratio of 1/6 g.mL(-1). Under these optimum conditions, the best dissolution yield was 98.26%.