The question is treated whether in the study of linear visco‐elastic behavior of a material change of temperature is completely equivalent to a shift of the logarithmic time scale or not. If it is, the material is termed ``thermo‐rheologically simple'' (classA).It is shown that, by plotting the results of a similar rheological experiment (for instance, a creep experiment) performed at different temperatures and comparing the curves obtained, one can decide whether the materials considered belongs to classAor not, by seeing whether the curves can be made to fit by shifting them along the axis of logarithmic time. Once the material has been decided to behave thermo‐rheologically simple, one can plot the function describing the time‐shift as function of the temperature.Some examples of thermo‐rheologically simple materials are quoted from the literature.The micro‐rheological conditions for thermo‐rheologically simple behavior are discussed. It turns out that this behavior implies that in similar deformations at different temperatures always the same sequence of molecular events follows, whereas in materials not belonging to classA, not only the speed, but also the sequence of molecular processes changes when the temperature of the experiment changes. This implies, that materials of classAcannot from a heat treatment assume a special structure which could not be obtained by one temperature, whereas for materials of classBa heat treatment can indeed result in a special structure. It is reasonable to expect that thermo‐rheologically simple materials will be found only among polymers containing no crystallites and no pronounced polar groups.