A theoretical framework for the computer simulation of all uncoupled diffusion processes was developed using network thermodynamics and bond graph techniques. Applications in the areas of membrane science and drug diffusion studies are illustrated. A new method of numerical analysis based on the bond graph model was developed employing a single exponential function. This was tested for several simple linear one dimensional diffusion problems. This method of integration was then used to produce computer simulations of ion exchange diffusion and swelling-diffusion systems based on non-linear bond graph models. A bond graph model for two dimensional diffusion was developed and validated for plane sheet diffusion and release from a limited cylinder. Several useful applications of these models are illustrated. A bond graph model for the simulation of three dimensional diffusion processes was also developed, therefore allowing the quantitative study of diffusion systems with complete assymetry. This bond graph model was tested for the simple example of diffusion from a cube.