Aromatic polymers such as poly(arylene ether)s, polyimides, polyamides, and polyazoles are important classes of high-performance polymers due to their outstanding set of physical and chemical properties. However, these polymers suffer from their poor processability, which limits their scope of application. Semifluorinated polymers containing bulky –CF3 groups are of special interest because they help to enhance the solubility and processability and increase glass transition temperatures without reducing the thermal stability. The incorporation of fluorinated groups reduces the interchain interaction and increases the fractional free volume, making the polymers suitable for microelectronics and for membrane-based applications. This chapter highlights the synthetic strategies and properties of the fluorinated polymers and their membrane-based applications. Major efforts towards the development of soluble semifluorinated polymers have been made by our group and this aspect is also covered in this chapter.