Understanding of moisture sorption isotherms of bioenergy crops is critical to monitoring their stability and quality during harvest, handling, transportation, and storage. Relationships between the moisture content (EMC) and equilibrium relative humidity (ERH) of four biomass crops - Miscanthus sinensis, miscane, energy cane, and energy sorghum -were determined at 15, 25, and 35 degrees C. Type II and type III isotherm characteristics were observed in all samples. The Henderson, modified Henderson, modified Chung-Pfost, modified Halsey, modified Oswin, and modified GAB models were applied to the individual energy crop's sorption isotherm data and a global isotherm model for the four energy crops was developed. Results showed that the modified Oswin model best fit the sorption behavior of the individual crops (0.974 <= R-2 <= 0.997 and 0.72% wet basis (w.b.) <= standard error (SE) <= 1.91% w.b.) and for a global isotherm model of these crops (R-2 = 0.973 and SE = 1.96% w.b.). When the soluble sucrose content (0.00-15.9%) of the energy crops were included the global isotherm model based on the modified Oswin equation, overall performance improved (R-2 = 0.979 and SE = 1.75% w. b.). (C) 2015 Elsevier Ltd. All rights reserved.