This chapter gives an overview of different methods that can potentially be used to determine the solubility of nanomaterials. In general, the methods presented can be broadly divided into four categories: separation methods, methods to quantify free ions, methods to quantify total dissolved species, and theoretical modeling/predictions. After presenting an overview of the different methods, a case study is presented. The aim here is to illustrate nanomaterial solubility measurement in the context of a specific nano-specific application. In particular, this case study explores the feasibility of microfluidics technology to measure solubility of ZnO. The device to be assessed is a miniaturized capillary electrophoresis (CE) with conductivity detection. The aim of the case study is to investigate as to whether such a device is fit for purpose and to determine if there is scope for further method development.