An alkaline solution is a mixture of base solids dissolved in water. It is a solution of a soluble base with a pH greater than 7. Alkaline solutions are also known as basic solutions. The pH scale measures the alkalinity or acidity level of a solution, and it ranges from 0 to 14. A neutral solution has a pH of 7, while pH levels below 7 indicate an acidic solution, and numbers above 7 indicate an alkaline solution. The pH scale indirectly measures the concentration of H+ ions in solution. Because alkalis have more OH- than H+ ions, their relative concentration of H+ is low, and so the pH value will be high.

Some examples of alkaline solutions include sodium hydroxide, potassium hydroxide, magnesium hydroxide, and calcium carbonate. Manufacturers commonly use alkaline solutions in products such as bio-diesel fuels, soaps, medications, detergents, and cleaning products. Additionally, manufacturers use alkaline solutions in many food preparations and specialized applications. As cleaning agents, alkaline solutions can dissolve fats, grease, oils, and protein.