Volume 7, Part A of Atomic and Plasma-Material Interaction Data for Fusion is devoted to a critical review of the chemical erosion behaviour of fusion plasma-facing materials, in particular carbon, beryllium and tungsten. It is intended to provide fusion reactor designers with a detailed survey and parametrization of existing, critically assessed data for the chemical erosion of plasma-facing materials by particle impact. This volume is the result of a five year Co-ordinated Research Programme on "Plasma-Interaction Induced Erosion of Fusion Reactor Materials" in the period 1992-1997. Contents: 1. Introduction; 2. Erosion data derived from tokamaks; 3. Carbon-based materials: Selected collection of chemical erosion data; 4. Comprehensive set of chemical erosion data from various laboratories; Appendix A: List of abbreviations; Appendix B: List of analytical fitting functions.