By the development of new, powerful radiation sources the so-called “THz gap” between MW and IR spectroscopy has been closed. This has allowed tackling new applications in various fields. First an overview over the progress over the development of new radiation sources in last years will be given. Then I will focus on applications using a high power laser p-Ge THz spectrometer. By measuring absolute absorption coefficients in the THz region we were able to determine the hydration dynamics of solvated sugars and proteins. Moreover, the setup of a THz cavity enhanced attenuated reflection spectrometer will be discussed. First applications include the investigation of surfaces and thin films.