Annual hydrographic monitoring of Hornsund fjord in southern Svalbard began in 2015. The observations span over several months, typically from May to October, each year. Vertical CTD (conductivity-temperature-depth) -profiles obtained regularly from 11 stations across the Hornsund fjord form the core of the hydrographic observations. The data has been collected using Valeport miniCTD and SAIV A/S SD208 CTD, of which the latter has been accompanied with oxygen and turbidity sensors. Thermodynamic variables (potential temperature, salinity, density and sound velocity) are derived from the raw data. The data has been filtered and the vertical profiles averaged to 1-dbar bins. The data has passed a careful visual quality control. Further details on the data collection and processing can be found in the manuscript mentioned below. The monitoring is still ongoing and the datasets will be updated annually at the data portal of Institute of Geophysics Polish Academy of Sciences (https://dataportal.igf.edu.pl/group/longhorn). The raw CTD-data is also available at the same data portal.