Future generation gas turbine combustors for power production are expected to have the capability of operating on a variety of different types of fuels. Energy systems running on different fuels produce flames with different burning behaviors, combustion dynamics, and pollutant emissions than when using conventional fuels. To ensure the implementation of new energy sources for future power generation units, which is critical for the US energy sector, lab-scale studies at high pressures and temperatures are being performed at many different locations throughout the world. Although many of these authors in the past present their results from the use of a high-pressure combustor, none have made their design methodology available to the public. Therefore, this paper presents a design of an optically accessible high-pressure combustor facility based on a 500 kW power and 1.5 MPa capability, which is the representative pressure of a gas turbine. Finite element analysis was extensively used to predict window and wall thicknesses needed to withstand these extreme conditions. Based on stress analysis quartz windows were designed with a thickness of 48 mm and a thickness of 8.61 cm was selected for the stainless steel combustor. Follow-up on testing using the high-pressure gas turbine combustor using various different types of fuels, diluents, and injectors have provided repeatable data on the capability of the combustor design to withstand the extreme environment conditions.