A program is being developed to calculate diffusion coefficients using the free-volume theory. The program is being developed using Microsoft® Visual C which provides for creating input and output data forms and user activated screen buttons. The current version allows the user to (1) input all parameters of the free-volume model and calculate diffusion coefficients or (2) input diffusivity data and have the program regress for selected parameters in the free-volume model. The results are presented in tabular and graphical form.