This study examines the behavior of a material under electro-mechanical loads arising of the external medium in a viscoelastic and dielectric material, provided that isotropy constraint is imposed on the material. The reaction of the object to external loads is expressed in elastic stress, dissipative stress and electrical polarization. Based on constitutive axioms and concepts pertaining to the symmetry group of the material, constitutive functionals have been obtained. To materially determine arguments of these functionals, findings of the theory of invariants have been used as a routine method. As a result constitutive equations pertaining to elastic stress, polarization field and dissipative stress have been found in material and spatial coordinates whereas symmetric and asymmetric stresses have been found in terms of displacement gradient and its derivative by using the expressions of elastic stress, polarization field and dissipative stress.