Groundwater Recharge Coefficient (Rcoef) for the European domain at 1 km spatial resolution for the period 1981-2010. The Rcoef estimate is based on a machine learning approach trained against gridded Rcoef estimates from seven national pilots in Europe. The Rcoef data set i part of a series of gridded datasets established in the TACTIC project for estimating Potential Groundwater Recharge (GWRpot). The data available are AET, Effective precipitation (Peff=Precipitation-AET), Groundwater Recharge coefficient (Rcoef defined as the ratio: Peff / GWRpot ) The Potential Groundwater Recharge GWRpot = (Precipitation-AET)*Rcoef. . Urban areas are masked out and not represented in the gridded dataset. Rcoef is a unitless ratio representing the period 1981-2010.