The elongational rheology of solutions of cellulose in the ionic liquid solvent 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was measured at 80, 90, and 100 degrees C; 8, 10, and 12 wt% cellulose; Hencky strains 5, 6, 7; and strain rates from 1 to 100 s(-1). Master curves were generated by shifting the elongational viscosity curves with respect to temperature and Hencky strain. Also, general master curves were generated by simultaneously shifting with respect to both temperatures and Hencky strain. From the Arrhenius plots of the temperature shift factors, the activation energy for elongational flow was deter-mined. The elongational rheology of these solutions was elongational strain rate thinning similar to that of their shear behavior and polymer melts and they were also strain hardening. Both effects and the viscosity increased with cellulose concentration. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 3203-3208, 2008