SUSS6.0 is a new 2023 release of the XMM OM Serendipitous Ultraviolet Source Survey catalogue. The catalogue was compiled for the Optical Monitor instrument on board the ESA XMM Newton observatory. This version, the 6th release of the catalogue, spans the period of observations from XMM-Newton revolution 34 (February 2000) to revolution 4207 (Novemver 2022). A detailed description of the Catalogue can be found at https://www.ucl.ac.uk/mssl/research-projects/2018/dec/xmm-newton. A refereed paper on the first version can be found in Page M.J. et al. (2012MNRAS.426..903P). In addition to covering a larger observation period, this sixth release reflects a change in philosophy with regard to the origin of the incorporated data. In previous releases, the data were generated via a bespoke processing of the OM Observation Data Files (ODFs) while in this new release, we have been guided by the XMM user community and we have sought to harmonize the contents of the catalogue with those of the OM data in the XMM-Newton Science Archive (XSA), which derive from the standard XMM-Newton pipeline processing system. While the bespoke processing and pipeline systems are fundamentally very similar, they are not identical and the differences lead to some differences in the output. All data have been fully processed at the European Space Astronomy Centre (ESAC, Madrid, Spain) using the XMM-Newton pipeline processing system (PPS) that invokes the XMM Science Analysis Software (SAS) - the vast majority of observations having been processed using SAS versions 18 and 19. The number of observations (OBSIDs) included in the catalogue is 12057. The total number of entries (detections) in this release is 9,920,390. They correspond to 6,659,554 unique sources, of which 1,225,117 have multiple entries in the source table, corresponding to different observations. The Catalogue is a FITS file consisting of two tables (please note that users wishing to use the TOPCAT tool to manipulate the catalogue, need to select the table format option, "FITS" to load the catalogue). The first table (SRCLIST) contains the source detections, with positional and photometric data (count rate, magnitude and flux) and quality flags for each measurement.