Microstructural and mechanical characterisation of Mg96Ni2Y1RE1 alloy have been performed in the 25–400 °C temperature range. The material was processed by melting, casting and subsequent extrusion at 400 °C. The microstructure of the extruded material showed the alignment of several phases (Mg12RE, Mg2Ni and a long periodic ordered phase) along the magnesium dendrites. This microstructure provides high strength up to 250 °C, which has been correlated with load transfer from the matrix to the intermetallic phases. At higher temperatures the material exhibits superplastic behaviour.