This paper relates the solubilities in 2% formic acid solution of various phosphate rocks used in Brazil, in function of the particle size and the relation of sample weight with extractor volume. The results were compared with 2% citric acid solution and wake possible the following conclusions: a) the classification in decreasing order of solubility for two extractors was bone degelatined flour, hyperphosphate (Africa phosphate), Florida phosphate, Olinda phosphate, Araxá phosphate and Alvorada phosphate; b) the Africa phosphate solubility is much higher in formic acid solution than in citric acid solution; c) the Florida and Araxá phosphates solubilities were similar for two extractors; d) the Olinda and Alvorada phosphates were slightly higher in citric acid solution than formic acid solution; e) the formic acid solution was more effective in the solubilization of bone degelatined flour than citric acid solution.