Changes in the mechanical properties during torsion of copper rods pre-deformed by rolling were correlated with crystallographic orientation distribution and mechanical stored energy changes, both being deduced from neutron diffraction measurements. The stress-strain relation under torsion demonstrated in its initial part a reduced range (I) of work hardening (work softening) in which important crystal re-orientations and small changes in stored energy were observed. The range of increased work hardening (II) was characterised by the formation of nearly perfect axial <111> + imperfect {100} axial texture components and by the increase of stored energy.