We investigate an immediate application in finite strain multiplicative plasticity of the family of isotropic volumetric-isochoric decoupled strain energieswhere ∂ χ is the subdifferential of the indicator function χ of the convex elastic domain Ee(Wiso, Σe, 1 3 σ 2 y ) in the mixedvariant Σe-stress space and Σe = F T e DF e Wiso(Fe). While W eH may loose ellipticity, we show that loss of ellipticity is effectively prevented by the coupling with plasticity, since the ellipticity domain of W eH on the one hand, and the elastic domain in Σe-stress space on the other hand, are closely related. Thus the new formulation remains elliptic in elastic unloading at any given plastic predeformation. In addition, in this domain, the true-stress-true-strain relation remains monotone, as observed in experiments.