The Blending Gas Delivery Module (GDM) delivers flexibility in gas handling on the Discovery TGA 5500 and TGA 550. The GDM is an external accessory with two additional gas inlet ports that connect to the reactive gas port on the TGA. The GDM used in conjunction with the TGA allows for automated switching between the gas ports, as well as software-controlled blending of binary mixtures of gases. The added capability to perform controlled blending of binary gas mixtures allows for TGA experiments to be carried out in an atmosphere where the concentration of gases may be in a fixed ratio, stepped incrementally or ramped at a controlled rate. The GDM is compatible with Nitrogen, Argon, Helium, Air, Oxygen, Carbon Dioxide, Carbon Monoxide and Forming Gas (4%H2/96% N2). This accessory can be used to study sorption of gasses onto a material at atmospheric pressure, Redox reactions, and thermal stability of materials in a controlled atmosphere.