Delayed and fluid oil sands cokes were used to prepare activated carbon through a fast activation process that uses microwave heating and KOH as activation agent. Activation parameters such as particle size, humidity of the purge gas, KOH to coke ratio, and microwave heating time were studied for their impact on the quality of the activated cokes obtained. The iodine number, specific surface area, scanning electron microscopic images, elemental analysis and X-ray photoelectron spectroscopy were used to characterize the activated coke obtained. Small particle size, presence of humidity in the purge gas, and high KOH/coke ratio provided higher iodine number and BET surface area. Longer microwave heating time increased the iodine number and surface area of the activated coke, but not monotonically. The differences in the properties of the activated delayed and fluid cokes are related to the structural differences and volatile content of the raw cokes. (C) 2012 Elsevier B.V. All rights reserved.