This volume is the eleventh in the OECD Nuclear Energy Agency (NEA) Chemical Thermodynamics series. It is based on a critical review of the thermodynamic properties of thorium, its solid compounds and aqueous complexes, initiated as part of the NEA Thermochemical Database Project Phase III (TDB III). The database system developed at the OECD/NEA Data Bank ensures consistency not only within the recommended data sets of thorium, but also amongst all the data sets published in the series. This volume will be of particular interest to scientists carrying out performance assessments of deep geological disposal sites for radioactive waste. Table of Content : - Introduction - Standards, Conventions and Contents of the Tables - Selected thorium data - Selected auxiliary data - Thorium elemental - The aqueous Th4+ ion - Thorium oxygen and hydrogen compounds and complexes - Thorium Group 17 (halogens) compounds and complexes - Thorium Group 16 compounds and complexes - Thorium Group 15 compounds and complexes - Thorium Group 14 compounds and complexes - Miscellaneous compounds and complexes - Appendix A - Discussion of selected references - Appendix B - Ionic strength corrections - Appendix C - Assigned uncertainties - Appendix D - The Gibbs energy minimisation and optimisation program, NONLINT-SIT - Appendix E - Spectroscopic constants and statistical mechanics calculations for gaseous species - Appendix F - Comment on the data for ZrO(g) and ZrO2(g) - Bibliography - List of cited authors