This work objective was compare the evapotranspiration of thecotton crop measure by the balance of energy and estimate by the Penman-Monteith (PM) model. Methods to calculate energy balance, mainly Bowenratio and Penman-Monteith (PM) model were applied. The values ofradiation varied from 8,50 W.m-2 to 642,06 W.m-2, with average of 251,01W.m-2. The crop resistance was 7.01 s.m-1to 333,33 s.m-1, with average 81.10s.m-1. The rainfall in the growing period was 347.20 mm during 150 dayswith a daily average approximately 2.31 mm. The daily evapotranspirationwas 0,27; 3,44; 3,50; 1,46; 1,53 and 3,02 mm.day-1 during the 52, 62, 83, 97,110 and 125 days after sowing (DAP), respectively. The results ofevapotranspiration obtained for the Bowen ratio method (ETB) werecorrelated with the results estimated by the Penman-Monteith model (PM),with R² = 0,97. The time of evapotranspiration verified by PM was 21%lower than that by ETB.
