The degree of neutralization, or basicity, of hydrolyzed Al³⁺ is expressed as the OH/Al molar ratio. This ratio is commonly referred to as the number of ligands, hydroxyl groups, or basicity (r). For aluminum chloride (AlCl₃), the r value is 0, while for aluminum hydroxide (Al(OH)₃), the r value is 3. In Polyaluminium Chlorides, the r value ranges between 0.5 and 2.5. The higher the r value, the more stable the product and the greater the number of polymeric molecules it contains. Thus, products with a high r value (high basicity) provide maximum coagulation efficiency.

Polyaluminium Chloride solutions are acidic, although the level of acidity decreases as the r value increases. The total aluminum content, expressed as Al₂O₃, provides information about the product’s composition and activity. The aluminum content (as Al₂O₃) in Polyaluminium Chloride products typically ranges from 7% to 24%. Depending on the derivatives, they may also contain different inorganic salts, and the presence of these inorganic species affects the quality and performance of the product.