The well-known interrelation between temperature- and frequency-dependent dynamic mechanical data of thermorheologically simple materials was further investigated to provide useful theological tools. Applicability of time-temperature superposition to isochronal dynamic mechanical temperature sweeps could be shown. Construction of master curves, b(T)G’(a(T) omega) and b(T)G "(a(T) omega), was possible from the isochronal data of two polymer samples, a commercial polycarbonate sample with temperature shift factors obeying the WLF equation and a commercial polyethylene sample with temperature shift factors following an Arrhenius expression, If the temperature dependence of the material’s relaxation times follows an Arrhenius-type expression, the activation energy can be obtained directly from plots of isochronal loss tangent versus reciprocal temperature. However, in case of a polymer following the WLF equation the shift factors (or parameters of the WLF equation) must be known for this construction to be feasible. Furthermore, it is shown that extension of the experimental temperature window is possible once the frequency master curve is created. An appropriate temperature- and frequency-dependent shift factor c(T) is introduced for this extension.