Abstract To optimize coffee ( Coffea arabica L.) production in Colombia, adaptation strategies that improve water use must be developed. Therefore, the objective of this study was to determine evapotranspiration under standard conditions (ET c ), reference evapotranspiration (ET o ), and the crop coefficient ( K c ) of coffee plants interplanted between maize ( Zea mays L.) (coffee–maize) for the first 12 mo of growth and coffee grown without maize from 13 to 46 m after transplanting (MAT). In this study, ET c was measured using the eddy covariance method. The ET c of coffee–maize ranged from 4.17 to 4.71 mm d –1 , while ET c of coffee–sun averaged 4.32 ± 0.07 mm d –1 between 13 and 24 MAT and 4.09 ± 0.03 mm d –1 between 25 and 43 MAT for coffee trees in the reproductive stage. The K c was 0.87 for coffee plants between 0 and 12 MAT, 0.98 ± 0.01 between 13 and 24 MAT, and 0.97 ± 0.02 between 25 and 43 MAT. Maize intercropped between coffee trees produced an adapted microclimate for the first 2 mo, allowing energy used for evapotranspiration processes (latent heat flux) to be greater than energy used for air warming (sensible heat flux), although there was low soil water availability. K c values are a foundation for optimizing coffee crop water use under climate and soil conditions for the intertropical Andean hillside region.