Hot deformation of cast-homogenized and extruded (in both the extrusion and transverse directions) ZK60 magnesium alloy was conducted using the Gleeble® 3500 thermal-mechanical simulation testing system. A new approach to model the high temperature constitutive behavior of the alloy was done using two well-known equations (ie hyperbolic sine and Ludwig equations). For this approach, the deformation conditions were divided into regimes of low and high temperature and strain rate (four regimes). Constitutive model development was conducted in each regime and the material parameters (P) were evaluated as strain, strain rate and temperature-dependent variables; P (ε, ε˙, T). Using this approach, the flow curves were predicted with high accuracy relative to the experimental measurements. Moreover, detailed information on the evolution of hot deformation activation energy was obtained using the modified hyperbolic sine model. Using the modified Ludwig equation, details of strain hardening and strain rate sensitivity of the ZK60 material during hot deformation were obtained.