Lignin, a complex and multifaceted organic polymer found in plant cell walls, plays a critical role in providing structural rigidity and resistance to environmental stress. This chapter delves into the function of lignin through nitration, a chemical modification process that introduces nitro groups (-NO2) into the lignin structure. The nitration process dramatically alters both the chemical and physical properties of lignin, enhancing its solubility, thermal stability, and mechanical strength while introducing new chemical reactivity. These modifications make dispersed lignin a versatile material with applications in diverse fields, including the production of explosives, polymers, adhesives, and energy materials. The chapter also discusses the structural transformations, thermal stability, and practical applications of nitro-lignin, highlighting its role in suppressing autocatalytic reactions and improving the stability of nitrocellulose-based materials. By providing insights into the chemical and physical evolution of lignin through nitration, this chapter underscores its potential for advanced materials science and industrial applications.