The effect of microwave irradiation on the comminution of two sulphide copper ores with different mineralogy were investigated to enhance the milling processes. Each ore was subjected to microwave radiation for varying time periods to determine their heating profiles. Changes in breakage characteristics with the microwave exposure time were quantified by sieving breakage, standard Bond work index grindability and single particle drop weight comminution tests. The results of the sieving breakage tests with the untreated and microwaved samples indicated significant improvements in the size reduction due to microwave energy induced macro fracturing. Differing ore mineralogy has been shown to affect the effectiveness of microwave assisted size reduction. The results of the standard Bond work index grindability tests performed with both the microwave treated copper ores, on the other hand, suggested no significant improvements in grindability. The single particle fracture experiments performed with an Ultrafast Load Cell (UFLC) indicated similar results of no significant improvements in the fracture energies of the microwave treated ore samples.