Presented at the GHRSST XXIII international science team meeting, 27 June-1 July 2022, online and in-person (Barcelona). #GHRSST23 Short abstract The first Copernicus Sentinel-3 satellite was launched on 16th February 2016 and the second on 25th April 2018. The Sentinel-3A/B satellites observe high quality Sea Surface Temperature (SST) from the Sea and Land Surface Temperature Radiometer (SLSTR). These accurate SSTs provide a reference satellite SST dataset and time-series for other satellite SST missions and are important for climate monitoring. Operational SLSTR SST products have been distributed from the EUMETSAT marine centre since 5th July 2017. EUMETSAT performs ongoing validation activities for SLSTR SST, together in coordination with the Sentinel-3 validation team, and real time monitoring is shown from the link to metis.eumetsat.int. Validation results show the products performing extremely well, and dual-view SSTs recommended to be used as a reference SST source, with some users already using SLSTR SST reference data. EUMETSAT began activities in 2021 towards revised and improved algorithms for SLSTR SST and sea-ice Surface Temperature (ST) with the intention of the operational implementation of SLSTR day-2 SST and day-1 sea-ice ST by 2025. This includes improvements to the Bayesian cloud-screening, retrieval coefficient updates, inclusion of depth SST in addition to skin SST, potential evolution to include full nadir grid, and the first operational implementation of sea-ice ST for SLSTR. Shorter term improvements, planned by 2023, include revised SST coefficients, updates to ADI and DDI tests, and updates to SSES scheme. A demonstrational sea-ice ST prototype processor has been implemented on the Copernicus WEkEO platform. Recent results and information on further ongoing projects and evolutions relating to Sea Surface Temperature at EUMETSAT will be presented. Ongoing validation activities are important for assessing and maintaining SLSTR SST product quality. In addition to inter-comparisons with other satellite SST, key components are collocations and analyses with drifting buoy SSTs. A Copernicus-funded EUMETSAT project called ‘Towards Fiducial Reference Measurements (FRM) of Sea-Surface Temperature by European Drifters’ (TRUSTED) is now in its fifth year. Over 150 high-resolution drifting buoys (HRSST-2), plus calibration per sensor, have been deployed so far. A service of measurements will continue at a rate of additional 25 buoys per year, with a focus at higher latitudes and other priority regions. Activities have also begun towards the requirements, design and prototype of sea-ice surface temperature drifting buoys needed for the validation of Copernicus satellite sea-ice surface temperature products. Activities continue to assess and validate these reference buoys as FRM for SLSTR together in coordination with the GHRSST HRSST Task Team.