Preferential ion sputtering of HgTe and HgCdTe is the dominant ion sputter effect observed in these material systems. There is little preferential sputtering of CdTe. The ion sputter behavior of HgCdTe can be predicted from the ion sputter behavior of HgTe and CdTe. The weakness of the Hg–Te bond compared to the Cd–Te bond accounts for the greater ion sputter rate of HgTe to CdTe and causes Hg to have a large relative ion sputter yield compared to the other elements and, most likely, plays a dominant role in the preferential sputtering of Te in HgCdTe. Preferential ion sputtering is dependent on the chemistry of Hg1−xCdxTe; elemental ion sputter yields depend on the amount of HgTe in the sample.