溶解性（英语：Solubility）是指一种物质能够被溶解的程度。发生溶解的物质叫溶质，溶解他物的液体（一般过量）叫溶剂，生成的混合物叫溶液。

定温定压下，固体溶质在100g溶剂中达到饱和状态时所溶解的质量称为溶解度。气体的溶解度则是指101Kpa、一定温度条件下，气体在1体积溶剂中达到饱和状态时的体积。

如果一种溶质能够很好地溶解在溶剂里，我们就说这种物质是可溶的；如果溶解度不高，称这种物质是微溶的；如果很难溶解，则称这种物质是不溶或难溶的。

实际上，溶解度往往取决于溶质在水中的溶解平衡常数。这是平衡常数的一种，反映溶质的溶解-沉淀平衡关系，当然它也可以用于沉淀过程（那时它叫溶度积）。因此，溶解度与温度关系很大，也就不难解释了。

Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance fundamentally depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure and the pH of the solution. The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration, where adding more solute does not increase the concentration of the solution and begins to precipitate the excess amount of solute. The solubility of a substance is an entirely different property from the rate of solution, which is how fast it dissolves.