Thermal processes are employed for the commercial regeneration of field-spent activated carbon media. The quality of the regenerated carbons is negatively affected by the presence of accumulated metals (particularly calcium) that catalyse the reaction between the regeneration agent (carbon dioxide or steam) and the solid carbon. Work presented in this paper investigates the pre-treatment of field-spent carbons at high temperatures under inert atmospheric conditions as a means of promoting sintering processes that reduce the catalytic activity of accumulated metals. For the purpose of this work, a sample of field-spent GAC was characterised for its metal content and heated to different temperatures (between 650 and 1200degreesC) using a laboratory-scale furnace. A series of thermogravimetric (TG) analyses were conducted to investigate the effect of thermal pre-treatment on the reactivity of the carbons when gasified under mildly oxidising conditions (carbon dioxide). The experimental results showed a progressive reduction in the carbon reactivity with the pre-treatment temperature. These changes were reflected in the activation energies (E-a) and pre-exponential values (A) of the samples, denoting a progressive reduction in the catalytic activity of the accumulated metals. Scanning Electron Microscopy-Emission Dispersive X-ray (SEM-EDX) analyses illustrated that this phenomenon may be attributed to sintering processes that affect the distribution of metals in the carbon particle.