Regenerated cellulose fibers were produced by dry-jet wet spinning from cellulose/1,5-diazabicyclo [4.3.0] non-5-ene-1-ium acetate solutions. Cellulose blends with different molar mass distribution but fixed intrinsic viscosity were employed as starting materials to investigate the influence of the cellulose molecular structure on the spinnability and the mechanical properties of the resulting fibers. The cellulose/ ionic liquid solutions were prepared from blends constituted of cotton linters and spruce sulfite pulp representing a polydispersity index from 2.0 to 5.9. Dynamic shear rheology was performed on the solutions to examine the effect of cellulose chain distribution on the visco-elastic behavior and to select the adequate temperature for stable spinning. The mechanical and physical properties of the resulting fibers were determined by tensile tests and birefringence measurements. Cellulose solutes having a share of high molecular weight cellulose (DP > 2000) higher than 20% and a minimum polydispersity index of 3.4 showed enhanced spinnability. Higher draw ratios were accessible, resulting in improved cellulose chain total orientation and high-tenacity fibers. (C) 2015 Elsevier Ltd. All rights reserved.