The first measurements of temperature and species distributions within the submerged reaction zone stabilized inside radiant burners made of reticulated ceramic matrices are reported. The radiant burners and the flames stabilized within them are characterized in terms of stability limits, radiation efficiencies, and global pollutant emission indices. In contrast to adiabatic flame behavior, a tendency of the burners to flash back with increasing firing rates was experimentally observed. This is in qualitative agreement with the predictions reported in the literature [8]. However, for the present equivalence ratio, the firing rate at flashback is approximately five times higher than typical estimates given in Ref. 8. The temperature and species profiles show that the reaction zone is very broad, and that the tendency to flashback results from higher preheating of the unburnt mixture. Quenching at the ceramic matrix strand surfaces was observed from local temperature and species data. The NOx emission indices of these burners are extremely low (0.1-0.35 g/kg). The CO and HC emission indices are slightly higher due to the quenching of reactions near the solid surfaces (CO: 0.1-3.6 g/kg, HC: 0.1-1.2 g/kg).