In order to transform chemical energy stored in organic matter into electricity, hydrogen, and value-added products, microbial electro chemical cell (MEC) technology combines electrochemistry, microbiology, and sustainable engineering. The principles of microbial fuel cells and microbial electrolysis cells, including metabolic processes, extra cellular electron transfer pathways, and the behavior of electroactive biofilms, are covered in detail in this book. Reproducible laboratory protocols for single-chamber MFC and MEC construction support the clear presentation of fundamental concepts like redox potentials, electrode reactions, reactor configurations, and operational optimization. These systems’ versatility is demonstrated by their applications in resource recovery, wastewater treatment, pollutant degradation, and microbial desalination. The book attempts to direct researchers toward dependable experimentation and sustainable bioelectrochemical innovation by fusing theoretical concepts with useful lab notes.