The Ketzin pilot site has been the longest-operating European onshore CO2 storage site. Between June 2008 and August 2013, a total amount of 67 kt of CO2 has safely been injected into a saline aquifer. The reservoir consists of 630 m to 650 m deep sandstone units of the Stuttgart Formation of Upper Triassic age. These were deposited in a fluvial environment (Förster et al., 2010). A sequence of about 165 m of overlaying mudstones and anhydrites is sealing the storage complex and act as caprock (Martens et al., 2012).The research and development programme at Ketzin is among the most extensive worldwide in the context of geological CO2 storage (Giese et al., 2009). Research activities have produced a broad data base and knowledge concerning the storage complex at Ketzin itself but also CO2 storage in general (Liebscher et al., 2013; Martens et al., 2011-2014; Würdemann et al., 2010; Schilling et al., 2009).This publication compiles the operational data (flow rate, cumulative mass, density, injection temperature, electrical conductivity and in-well pressure data) recorded during a field experiment on brine injection at the Ketzin pilot site during October 2015 to January 2015. Anyone should feel free to make use of the published data for any ethical purpose (civil use) – for example for process modelling and engineering.