Bio-hydrometallurgy is the hybridisation of biotechnology and metallurgy. From unique properties of some potentially signicant biotopes and active principles of interactions between microbial metabolisms and materials, ef- cient integrated bio-metallurgical processes have been developed to extract metals (Morin et al., 2006). The hybrid process may involve a sequence in which a substance (ore/mineral/waste and by-product) is treated by applying a bio-leaching/bio-beneciation approach followed by chemical processing or vice versa. Early practical applications of bio-hydrometallurgy entailed dump leaching of low-grade, low-value and run-of-mine material. Modern practical applications of bio-hydrometallurgy became a reality in the 1950s with the advent of copper bio-leaching at the Kennecott Copper BinghamCONTENTS14.1 Introduction 359 14.2 Fundamental and Alternative Routes of Hybrid Bio-Leaching 360