1km resolution gridded potential evapotranspiration over Great Britain for the years 1961-2012. This dataset contains time series of two potential evapotranspiration variables. The first is potential evapotranspiration (PET) (mm/day) calculated using the Penman-Monteith equation [1] for FAO-defined well-watered grass [2]. The second is potential evapotranspiration with interception correction (PETI) (mm/day), which adds a correction for interception by a well-watered grass on days in which there is rainfall. Both PET and PETI are calculated using the Climate Hydrology and Ecology research Support System meteorology dataset (CHESS-met) meteorological variables [3]. [1] Monteith, J. L.: Evaporation and environment, in: 19th Symposia of the Society for Experimental Biology, University Press, Cambridge, 1965 [2] Allen, R. G., Pereira, L. S., Raes, D., and Smith, M.: Crop evapotranspiration - Guidelines for computing crop water requirements, Food and Agriculture Organization of the United Nations, Rome, Italy, FAO Irrigation and Drainage Paper, 1998. [3] Robinson, E. L., Blyth, E., Clark, D. B., Finch, J., Rudd, A. C. (2015). Climate hydrology and ecology research support system meteorological dataset (1961-2012) [CHESS-met] . NERC-Environmental Information Data Centre https://doi.org/10.5285/80887755-1426-4dab-a4a6-250919d5020c