Shipping activities across the Artic are expected to increase with decreasing sea ice cover, thus increasing the risk of oil spills. Heavy Fuel Oil (HFO, a mixture of residual fuel and distillate diluent) is often used as fuel in marine vessels as it is relatively cheaper than e.g. lighter marine fuels. Knowledge about fate and behaviour of HFOs is important to select the most efficient countermeasures in an oil spill situation as well as in the risk assessment of possible oil spills in cold waters. The aim of this review is to collate and strengthen the knowledge base on HFO in cold seawater, its fate and behaviour, including weathering, biodegradation, environmental implications of HFO spills and HFO spill response including environmental considerations regarding use the of chemical dispersants and in situ burning. Knowledge gaps and research needs are identified and described.