Thermal conductivity is one of the main properties of any materials as it plays a key role for their use in a wide range of essential applications. This book covers emerging fluids like ionic liquids and suspensions of nanoparticles known as nanofluids. Despite being a popular topic under rapid evolution, knowledge on thermal conductivity of nanofluids is far from being mature. Besides discussion on various mechanisms and modeling, this book presents experimental findings related to the impact of various parameters on the thermal conductivity of these new fluids. It includes thermal conductivity of ionanocolloids which is a new type of nanofluids. The book is aimed to serve as a guide to research, education, and industries in the fields of heat transfer and exchange, cooling, and other thermal management.