Analysis of heat transfer and thermal stability in a stockpile of reactive material is studied theoretically by using mathematical approach. The study can be modelled in a rectangular slab, a cylindrical pipe or a spherical domain. A reactive material is any carbon containing substance, like coal or hay, that combusts automatically in the presence of oxygen due to exothermic chemical reaction also called low temperature oxidation. The aim of the book is to show how mathematics is applied to bring understanding of the complicated process of combustion. The study is motivated by pollution of the environment due to emission of the greenhouse gas, carbon dioxide, and heat release in self-ignited fires of reactive materials such coal stockpiles. The release of heat and emission of carbon dioxide, among others, are the major causes of global warming and climate change. The theoretical approach is cheaper and quicker to give results as compared to experimental one. The programming for each study is provided to allow the reader to extend the concept of heat transfer analysis.