From January 2016 until August 2018, an automated Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS) instrument was operated at the German research station Neumayer III (NMIII) in coastal Antarctica to measure trace gas mixing ratios in the boundary layer close to the ground (average altitude above the snow surface: 4m). Two different atmospheric light paths with total lengths of 3100 m and 5900m were used depending on visibility.The DOAS evaluation of OClO was performed between 301.7 and 346.4 nm as well as between 332.5 and 370.5 nm (for subsequent measurements in two different instrumental setups). Fits with residual optical density RMS (root mean square) values larger than 3.5e-4 and 2.5e-4 respectively were discarded. The resulting mean residual RMS are 1.7e-4 and 1.4e-4 respectively. The mean detection limits of the two evaluations are 3.8 and 3.9 pmol/mol.The data sets include the observations below the respective detection limit scattered around 0, which due to the spectral analysis with the DOAS approach can include negative values. Significant data points can be selected using the separately provided detection limits (3-sigma criterion - recommended). Alternatively, the total errors can be used.The mixing ratios provided here were calculated using meteorological data from Neumayer III station already published on PANGAEA. A list of data sets is included in the "Related to" section of the bibliography this data set is part of.The spectral raw data of the measurements is stored on the measurement data server of the Institute of Environmental Physics, University of Heidelberg.