Abstract: Understanding the temperature dependent deformation behavior of Mg alloys is crucial for their expanding use in the aerospace sector. This study investigates the deformation mechanisms of hot-rolled AZ61 Mg alloy under uniaxial tension along rolling direction (RD) and transverse direction (TD) at –50, 25, 50, and 150°C. Results reveal a transition from high strength with limited elongation at –50 °C to significant softening and maximum ductility at 150°C. TD samples consistently showed 2%–6% higher strength than RD; however, this yield anisotropy diminished at 150°C due to the shift from twinning to thermally activated slip and recovery. Fractography indicated a change from semi-brittle to fully ductile fracture with increasing temperature. Electron backscattered diffraction (EBSD) analysis confirmed twinning-driven grain refinement at low temperatures, while deformation at high temperatures involved grain elongation along shear zones, enabling greater strain accommodation before material failure.