The present investigation deals with the study of two-dimensional fundamental solution in orthotropic piezothermoelastic diffusion media. By virtue of the two-dimensional general solution of orthotropic piezothermodiffusion elastic media, the fundamental solution for a point heat source and chemical potential source on the surface of a semi-infinite orthotropic piezothermoelastic diffusion plane is constructed by five newly introduced harmonic functions. The components of displacement, stress, electric displacement, electric potential, temperature change and chemical potential are expressed in terms of elementary functions. The components of displacement, electric potential, temperature change and chemical potential are computed numerically and depicted graphically. From the present investigation, a special case of interest is also deduced to depict the effect of diffusion.