Five polyaromatic sulfonate compounds, 1,3,6,8-pyrene tetrasulfonate, 1,5-naphthalene disulfonate, 1,3,6-naphthalene trisulfonate, 2-naphthalene sulfonate, and 2,7-naphthalene disulfonate, were tested for use as geothermal tracers. They were subjected to a simulated hydrothermal environment in batch autoclave reactors in order to determine their thermal decay kinetics. The decay kinetics study indicated that all of the compounds are suitable for use in reservoirs having temperatures up to 310 degreesC, whereas some are suitable for use in reservoirs as hot as 350 degreesC. Methods were developed for the chemical analysis of the polyaromatic sulfonates and their detection limits were shown to be approximately 200 parts per trillion by conventional high-performance liquid chromatography. The tracers were successfully tested in a series of field studies at Dixie Valley, Nevada; Steamboat Springs, Nevada; Ohaaki, New Zealand; and Awibengkok, Indonesia.