The heat produced by incremental adsorption of toluene vapor on two activated carbons has been investigated by flow microcalorimetry (FMC). One carbon is primarily microporous with 85% of its pore volume associated with micropores, whereas, mesopores account for 75% of the pore volume in the second carbon. Both integral and molar heats have been determined for adsorption of toluene in a partially filled pore system in the pore fill fraction range from 0.5 to 0.95. The carbon samples were diluted with polytetrafluoroethylene powder in order to improve the flow/heat transfer characteristics of the system and decrease the thermal response time of the calorimeter. Thermal response profiles were de-convoluted in order to relate the time evolution of the response to dynamic adsorption processes,