The aim of this thesis is the investigation, comparison and development of innovative techniques for the measurement of the activity concentrations of Radon (Rn-222), Thoron (Rn-220) and their parent nuclides. For this purpose, measurements of radon and thoron in soil air and indoors are taken in the Austrian Wald- and Mühlviertel and in the radioactivity laboratory of the Federal Office for Metrology and Surveying (BEV) in Seibersdorf. Additionally, the radon content in water samples is determined using an ionisation chamber and the activity concentrations of radionuclides of the uranium-radium and the thorium decay chains in soil samples is measured using low-level gamma spectrometry. In the course of the comparison of different measurement techniques, the measurement uncertainties and with that, the accuracy and precision of the measurement techniques are also investigated. The results of this thesis serve as a scientific basis for the practical applications of radon and thoron measurements. This thesis will be operated in cooperation with the Federal Office of Metrology and Surveying (BEV).