Nanoelectromechanical systems (NEMS) are a promising novel technology for operation in extreme conditions (e.g. high temperature and radiation levels), where complementary semiconductor technology devices might fail due to electronic instability. An example for a NEMS device is a nanowire-based switch, which employs mechanical deflection of a nanowire to open and close an electrical circuit. To date, assembly and operation of individual nanowire based NEMS switches have been successfully demonstrated at laboratory level, but their further technological development remains a challenge. This chapter gives an insight into the current advances in applications of nanowires for NEMS switches. Synthesis, electrical and mechanical tests of the nanowires, their assembly in nanodevices, investigation of nanocontacts and optimization of switching parameters are discussed. Particular attention is devoted to characterization of mechanical properties of various semiconductor, such as germanium (Ge), bismuth selenide (Bi2Se3) and copper oxide (CuO) nanowires, and their operation as NEMS switches.