Hot workability characteristics of a recently developed rare-earth-free creep-resistant magnesium alloy Mg-3Ca-2Sn-1Al (XTA321) is evaluated using the processing map approach. The processing map is established using the flow stress data from constant strain rate compression tests conducted in the temperature and strain rate range of 300°C-500°C and 10−3-10 s−1, respectively. The processing map exhibits a hot workability domain between 475°C to 500°C and in the strain rate range of 10−2 to 10−1 s−1. Correlation of post-deformation microscopy with kinetic analysis is carried out to identify the possible softening mechanism in the hot working domain. The significant portion of the processing map falls in the instability regime, having shear band formation as the prime microstructural feature. The poor workability of the XTA321 vis-a-vis most of the magnesium alloys can be attributed to the presence of a high volume fraction of the strong second phase in the microstructure. Copyright © 2020 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959