This learning module is concerned with the temperature field, the heat transfer rates, and the coolant pressure drop in typical high temperature gas-cooled reactor (HTGR) fuel assemblies. As in all of the modules of this series, emphasis is placed on developing the theory and demonstrating its use with a simplified model. The heart of the module is the HTGR Thermal-Hydraulics Computer Code which solves for the radical temperature distributions in the fuel, moderator, and coolant at any axial station and then marches axially with an energy balance in the coolant. The code and its use are described in detail including a listing and definition of all variables, a discussion of all input requirements and resulting output, an annotated flow chart of the code, an explanation of all options in the code, and a listing of the code which gives enough comment statements to clearly indicate the operational steps being performed. By proper specification of the option, the code can either be used as an individual entity to study thermal-hydraulic aspects exclusively, or as a subroutine in the total HTGR module package to provide temperature feedback to the other modules. Examples are worked out using the code. (Author/SK)