Low temperature thermal treatments of CdHgTe, normally in the presence of mercury vapor, are still used on both bulk samples and single and multi-layer epitaxial layers to modify or control the electrical properties. This paper reviews the recent literature reports in this area and develops the existing model to explain certain features of the p to n conversion process. A brief update on compositional interdiffusion at low temperatures is given which shows significant disagreement within literature values. In addition, the paper will describe and comment on some as yet unexplained results (interdiffusion and electrical behavior) following low temperature treatments in both liquid phase and metalorganic vapor phase epitaxial (LPE and MOVPE) layers.