ABSTRACT Chromatography is a crucial technique in various industries, particularly in pharmaceuticals, where it is used to separate, purify, and analyse compounds. Ion exchange chromatography (IEC) is a type of chromatography that separates ions based on their electrostatic interactions with a stationary phase. The technique is widely used in biotechnology, pharmaceutical processing, and water treatment. IEC is essential for the purification of charged proteins, nucleic acids, and other biomolecules. The separation process involves the interaction between ions and a charged stationary phase, allowing for the selective retention and elution of ions. The technique has various applications, including the purification of proteins, peptides, enzymes, nucleotides, and DNA. IEC is also used in the food industry to adjust the pH of liquid media and extract important components. The instrumentation of IEC includes columns, sample injection systems, mobile phase reservoirs, pumps, detectors, and data systems. Overall, IEC is a powerful tool for the separation, purification, and analysis of ions and biomolecules, and its applications continue to grow in various industries. Keywords: Ion exchange; Resin; Anion exchange; Cation exchange.