Sediment flux measurements have been conducted in Hornsund fjord in southern Svalbard since 2016. The observations span over several months, typically from May to October, each year. The main focus of the sedimentological observations has been on Hansbukta, one of the several smaller fjord arms in Hornsund fjord. Intermittent observations from other locations across the fjord are also available. Sediment flux measurements are obtained from a single point in the center of Hansbukta. In individual years, the distribution of sedimentation has also been surveyed with sampling across sections parallel and perpendicular to the glacier front. The sediment flux is generally measured either 5 meters above the bottom or below/above the thermocline. The amount of organic matter, expressed as loss on ignition (LOI %), is obtained after combustion. 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).