In present study, the deformation in a micropolar thermoelastic diffusion medium due to thermal source by the use of finite element method (FEM) is investigated in the context of Lord-Shulman (L-S) theory of Thermoelasticity. A special type of sources have been taken to show the utility of the approach. The components of displacement, stress, microrotation, temperature change and mass concentration are computed numerically and depicted graphically to show the impact of micropolarity, diffusion and relaxation times. Some particular and specials cases are also deduced from present investigation.