The paper is concerned with the numerical simulation of thermomechanical processes for linear viscoelastic solids with special consideration of the dissipative coupling phenomena. A constitutive equation is based on a four-parameter model, the so-called Kelvin-Maxwell model. The fully coupled finite element formulation follows from the mixed thermomechanical boundary- and initial value problem through the usual time and spatial discretization procedures. A simultaneous solution strategy yields the unknown values describing both the mechanical and the thermal field. Illustrative examples, involving static and cyclic loadings, exhibit the viscoelastic behaviour of the material and show the efficiency of the numerical method within the scope of thermomechanics.