Experimental values for the solubilities of three alkaline salts of hexafluorosilicate (K2SiF6, Na2SiF6 and (NH4)2SiF6) in different acidic solutions are reported as a function of the acid concentration in the solution. The acids used for this Letter are hydrofluoric, hydrochloric, sulphuric and nitric acids. The solubilities of the three studied compounds present important variations according to the nature and the concentration of the acidic solution. The presence of these acids influences the ionic strength of the solution, which plays an important role on the solubilisation of the three studied hexafluorosilicates. Fit curves have been elaborated to characterize the solubilisation phenomenon of the three compounds in the studied acidic solutions.