Stearic acid also called octadecanoic acid is one of the many useful types of saturated fatty acids that comes from many animal and vegetable fats and oils. It is a waxy solid that melts at around 70°C and its chemical formula is CH3(CH2)16COOH. Its name comes from the Greek word, stear, which means tallow.

Stearic acid is prepared by treating animal fat with water at a high pressure and temperature. It can also be obtained from the hydrogenation of vegetable oils. Stearic acid is useful as an ingredient in making candles, soaps, and cosmetics and for softening rubber.