The combination of light weight and excellent mechanical properties makes Mg alloys containing rare earths very promising materials for lightweight construction. However, the wider use of these alloys in structural applications relies on the optimisation of their forming parameters, which requires a systematic study of the mechanical behaviour and the microstructural changes during deformation at typical forming conditions. In this work, an extruded Mg alloy was tested in compression using a Gleeble system at high temperatures (350, 400, 450 and 475 ºC) and strain rates (0.3, 1, 3, 10, 30 and 50 s-1) in order to simulate forming operations. Afterwards, the heterogeneity of deformation during hot compression and the accompanied dynamic recrystallization processes were investigated by examining the microstructure of the tested samples. The experimental compression data allowed the determination of the Garofalo equation, best describing the hot deformation behaviour. This constitutive equation was later used to construct the forming maps of the MN11 alloy, which define regions of flow instability and free of damage and thus determine the safe conditions of temperature and strain rates. The predicted formability behaviour was validated with the results of the microstructural characterisation of the compressed samples.