The combustion behavior of polymethylmet hacrylate (PMMA) in a solid fuel ramjet (SFRJ) was investigated using a connected pipe test facility. The study was oriented towards understanding the most important phenomena related to the combustion in an SFRJ. Regression rates have been determined, and spectroscopy has shown the occurrence of OH, C2, and CH. Combustion pressure was shown to affect soot formation. No grain length effect on regression rate could be detected, whereas oxygen content in the air and inlet air temperature are important. Temperatures in the center of the bore are about 900 K, while temperatures in the recirculation zone approximate 1400 K. The highest temperatures were found in the near-wall region downstream of the recirculation zone. The combustion efficiency varied between 70% and 90%, and may be increased by increasing the fuel grain length and/or the oxygen content.