© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Hypersonic flows become popular due to its use in space explorations and military applications. It occurs normally, when a space craft re-enter to the atmosphere. Space crafts are exposed to high temperatures and high pressures because of Earth’s atmosphere and gravity. In addition in high temperatures, gases tend to react with each other. These reactions also have effects on space craft’s surface. In order to calculate these effects, all physical phenomena must be calculated. One of these phenomena is diffusion. Diffusion can be identified as movement of the species (O2;N2; ie:). There are various models for diffusion like Fick’s Law of Diffusion and Stefan-Maxwell Diffusion Equation. diffusion calculation, diffusion coefficient or diffusivity plays an important role as conductivity constant. There are also different models for calculating the diffusivity like, Constant Lewis Number method, Binary Collision Theory. In this study, Apollo AS-202 Command Module is selected as a re-entry space craft. Structural grid is applied around the geometry. Newton-GMRES method is used to solve flow field.