This chapter focuses on the experimental apparatuses and the experimental tests used to study high-temperature flow of rocks and minerals. Three distinctly different types of apparatus—one-atmosphere, gas medium, and solid-medium systems—are used to investigate the high temperature deformation behavior of rocks and minerals. Details of the design and operation as well as the advantages and limitations of each type of apparatus are discussed in the chapter. All three types of equipment are required to study the wide range of problems which are of interest in the solid earth sciences. However, the chapter emphasizes on the gas-medium and one-atmosphere apparatuses, because of the importance of high-pressure experimentation in rock mechanics. Probably the most mechanically complex types of apparatus available for studies of the flow behavior of rocks and minerals at high pressures are those employing a gas confining medium. High-temperature compressive creep experiments at a total pressure of 1 atmosphere, which involve the least complicated of the three types of experimental apparatus, have been used for the past decade to study flow of olivine and quartz single crystals. There are several advantages to performing deformation experiments without a confining pressure.