This training course will give an introduction to TOUGHREACT. Application examples to problems such as reactive transport in groundwater and CO2 geological sequestration and geothermal system, will be provided. The course will also include a survey of the physical and chemical processes modelled, and of the mathematical and numerical approaches used. The focus will be on enabling users to prepare input data for setting up and solving problems, and on emphasizing their role as prototypes and templates for creating new applications.