Microwave radiometers are part of the standard instrumentation at primary NDSC stations and are due to their long-term stability and self calibrating technique especially useful for monitoring purposes. Altitude profiles are retrieved from the shape of the pressure broadened thermally induced emission line of the observed species. The instruments for the observation of stratospheric ozone, chlorine monoxide and water vapour at the Koldewey Station in Ny-Ålesund were developed at the University of Bremen and upgrades and improvements are regularly carried out. The instruments have been automated during recent years and ozone and water vapour observation on Spitsbergen are carried out all year round. Chlorine monoxide is only observed in late winter and early spring, when enhanced concentrations in the lower stratosphere are to be expected. Routine operation and maintenance are done by the station engineer. Data analysis is carried out at the University of Bremen.