This chapter provides an overview of the biodegradation and biological treatments of cellulose, hemicellulose, and lignin, which are major components of lignocellulose. Lignocellulose, comprising about half of the biomass produced by photosynthesis, consists of these three polymers that are chemically bonded by non-covalent and covalent forces. Various microorganisms, including fungi and bacteria, can degrade these polymers using a suite of hydrolytic and oxidative enzymes. The chapter highlights recent advancements in biological treatments that convert these biopolymers into alternative fuels, such as ethanol, and discusses the potential of using lignocellulolytic enzymes in pulp and paper manufacturing to reduce environmental impact. It also explores the use of microorganisms for de-inking and toner release from office waste. The structure and composition of lignocellulose materials, particularly wood, are described, emphasizing the roles of cellulose, hemicellulose, and lignin in the plant cell wall.This chapter provides an overview of the biodegradation and biological treatments of cellulose, hemicellulose, and lignin, which are major components of lignocellulose. Lignocellulose, comprising about half of the biomass produced by photosynthesis, consists of these three polymers that are chemically bonded by non-covalent and covalent forces. Various microorganisms, including fungi and bacteria, can degrade these polymers using a suite of hydrolytic and oxidative enzymes. The chapter highlights recent advancements in biological treatments that convert these biopolymers into alternative fuels, such as ethanol, and discusses the potential of using lignocellulolytic enzymes in pulp and paper manufacturing to reduce environmental impact. It also explores the use of microorganisms for de-inking and toner release from office waste. The structure and composition of lignocellulose materials, particularly wood, are described, emphasizing the roles of cellulose, hemicellulose, and lignin in the plant cell wall.