AA 5005 was deformed in torsion to define the characteristics in the range 250-500 degrees C and 0.1-10 s(-1). This dilute alloy has higher workability than richer AI-Mg alloys, being markedly better than the Mn-bearing alloys 5083 and 5182. The constitutive constants were optimized by varying the stress multiplier over the range 0.02 to 0.08 MPa-1. The activation energy was stable in the center of that range and was far above that of Al near to Al-Mg-Mn alloys.