The hot working characteristics of as-cast Mg-3Sn-1Ca alloy have been studied using processing-map technique and the kinetic rate equation. The map exhibited two domains; one in the lower strain rate range (0.0003-0.01 s^{- 1}) and the other in the higher strain rate range (0.1-10 s^{- 1})-both falling in the same temperature range of 350-550 s^{- 1}. Hot extrusion at 500 °C and a speed corresponding to an average strain rate of 3 s^{- 1} exhibited dynamically recrystallized microstructure. The estimated apparent activation energy values are higher than those for self-diffusion in pure magnesium suggesting that the large volume fraction of MgSnCa intermetallic particles causes significant back stress.