Microcrystalline cellulose (MCC) is extensively used in pharmaceutical formulations due to its exceptional functionality as a diluent, dry binder, disintegrant, and absorbent. Despite being marketed in numerous grades that vary in particle size, source, extraction techniques, and co-processing methods, its basic chemical structure remains consistent across grades, with differences primarily in physical properties. This study investigates moisture sorption and desorption behavior and its effects on solid-state properties of thirteen different MCC grades, including eleven regular and two co-processed varieties, as moisture content significantly influences compaction, tensile strength, and viscoelastic properties.