棕榈酸（Palmitic acid），又称软脂酸，IUPAC名十六（烷）酸，是一种饱和高级脂肪酸，以甘油脂的形式普遍存在于动植物油脂中，在自然界中分布很广。棕榈油、棕榈仁油、牛油、奶酪、牛奶及肉类与多种植物油均有着这种脂肪酸，母乳中含量亦相当丰富。

工业上由牛油、猪油等动物脂肪或棕榈仁油等植物油经皂化后制得； 棕榈酸阴离子是棕榈酸在生理酸碱值中的观察型态。

棕榈酸是第一种从脂肪生成中产生的脂肪酸，亦可以由它产生更长的脂肪酸。棕榈酸盐对乙酰辅酶A羧化酶有负面反应，乙醘辅酶A羧化酶是在发展的醘链中负责将乙醘携带者蛋白转为丙二醘携带者蛋白，因而可以阻止棕榈酸盐的生成。

Palmitic acid, or hexadecanoic acid in IUPAC nomenclature, is the most common fatty acid (saturated) found in animals, plants and microorganisms. Its chemical formula is CH₃(CH₂)₁₄COOH. As its name indicates, it is a major component of the oil from palm trees (palm oil), but can also be found in meats, cheeses, butter, and dairy products. Palmitate is a term for the salts and esters of palmitic acid. The palmitate anion is the observed form of palmitic acid at physiologic pH (7.4).