Thermo-oxidative erosion rates of DIII-D and JET codeposits were measured as a function of oxygen pressure (0.21-21 kPa) at three oxidation temperatures (523, 573, and 623 K). The initial D removal rate during oxidation was observed to depend strongly on temperature and pressure (rate increases with increasing temperature and pressure). However, at 623 K the pressure dependence saturates for pressures >2 kPa. The final D content after prolonged oxidation, on the other hand, strongly depends on temperature and pressure in all cases---D content drops with increasing temperature and pressure.The UTIAS thermo-oxidation facility was also used to measure the 13C content of tiles exposed to injection of 13CH 4 into DIII-D plasmas. Although the technique appears to remove 13C (mostly via 13CO formation with little or no 13CO2), the measurements are suspect due to the technique's inability to conclusively exclude extraneous contributions to the mass 29 quadrupole mass spectroscopy signal.