Solid biofuels, in different trading forms, constitute an integral component of the energy mix of almost all developed and developing countries. Either in the form of pellets, briquettes, chips, firewood, or even as raw feedstock, solid biofuels are used mainly in the heating and power sector. Numerous sustainability concerns, focusing on the environmental, economic and technical aspects of solid biofuels exploitation, led to considerable advances in the recent years in this field. These developments mainly focus on the pre-treatment processes of the solid biomass to biofuels chain, the minimum requirements of the produced solid biofuels, as well as the efficiency and the environmental performance of their thermochemical conversion routes. This work aspires to provide the state of the art in the field of the exploitation of solid biofuels to present the main advances as well as the major challenges of this scientific fields. The topics presented in this book were examined and dealt with by the authors in the past few years, in numerous research projects and scientific publications. This book compiles all the assembled experience of the past few years, and aims to provide an overview of the solid biofuels exploitation field.