It has been shown that very short exposures to a high level of microwave power lead to reductions in ore strength. In this paper, the influence of modulated microwave power on copper ore breakage has been investigated. This approach to power delivery is applied to ascertain whether the strength of porphyry copper ore can be reduced with lower average modulated power levels than using continuous power. Changes in resistance to breakage of the treated and untreated ore were quantified by comparative drop weight tests. Mineralogical investigation for the ore was carried out with the Mineral Liberation Analyser (MLA) for surface identification of minerals and X-ray tomography for volumetric analysis. The comparative drop weight tests showed that material treated for 5 s at 5 kW of modulated power was weaker than untreated material. However, for this particular low grade ore, the degree of breakage which was achieved could be achieved with substantially less mechanical energy. It is possible that by using much higher level of microwave power, better liberation might be achieved than using conventional methods.