Abstract <p>The objective of this study is to examine the influence of initial stress on an isotropic medium, within the framework of Green-Naghdi thermoelasticity theory (Type II). A time-dependent mechanical load is applied to the free surface of the medium, and analytical solutions for the resulting thermal stresses, displacement, and temperature fields are derived using the Lame’s potential and normal mode analysis. Numerical simulations, implemented through MATHEMATICA programming, are conducted for a representative material to validate the theoretical model. The results are presented graphically to highlight the effects of various parameters, and initial stress, on the thermoelastic response. From the distributions, it can be found the wave type heat propagation in the medium. A comparison is made with the results obtained in the presence and absence of the initial stress. These findings offer significant insights for advanced engineering and scientific applications, especially in geophysics, aerospace, and biomedical engineering, where complex multiphysical interactions and initial stress effects play a critical role. The study also contributes to the ongoing development of generalized thermoelastic models capable of accurately capturing wave propagation and heat conduction behaviours in isotropic and homogeneous materials.</p>