Refuse derived fuel (RDF) represents a very robust and endogenous resource that has the potential to minimize landfilling of solid waste, reduce greenhouse gas emissions through its biogenic component and contribute to national energy provision whilst diversifying solid fuel supplies. This waste derived fuel can be produced from different waste streams after significant mechanical and biological processing. In spite of their processing, these waste derived fuels still have a high degree of heterogeneity, presenting variable fuel properties and some negative characteristics such as high moisture, ash and chlorine contents. Although RDF is used for energy generation in some high energy demanding industrial applications or dedicated energy recovery facilities, its physical-chemical characteristics can result in significant technical and environmental problems that may benefit from an upgrading treatment. Torrefaction and carbonization are thermal treatments that have the potential to upgrade RDF, producing a waste derived char with reduced moisture and chlorine contents, more homogeneous and friable, which are characteristics of great importance for feeding systems in gasification and combustion facilities. Using waste derived chars could result in major environmental and waste management advantages, with potential to help with the waste management crisis, reducing waste volume and corresponding to the present European guidelines for energy recovery from wastes, fitting perfectly in the concept of circular economy.