魔酸，是较早发现的超强酸之一，称它有魔法是因为它能够分解蜡烛中的蜡。魔酸是一种路易斯酸五氟化锑和一种质子酸氟磺酸的混合物。氟磺酸和五氟化锑按1:0.3（摩尔比）混合时，它的酸性是浓硫酸的1亿倍（哈米特酸度函数 = − 19.2）；按1:1混合时，它的酸性是浓硫酸的10亿倍。能溶解不溶于王水的高级烷烃蜡烛。

酸碱中和反应的实质是质子的传递反应。超强酸是指酸性比100%硫酸强的酸。魔酸（HSO₃F-SbF₅）是已知最强的超强酸之一，许多物质（如H₂SO₄）在魔酸中可获得质子（即质子化）。

SbF₅和HF以0.2:1的摩尔比混合时酸度以达到100%硫酸的10倍以上，随着SbF₅的比例增加酸度还能增强。

Magic acid (FSO₃H·SbF₅) is a superacid consisting of a mixture, most commonly in a 1:1 molar ratio, of fluorosulfuric acid (HSO₃F) and antimony pentafluoride (SbF₅). This conjugate Brønsted–Lewis superacid system was developed in the 1960s by the George Olah lab at Case Western Reserve University, and has been used to stabilize carbocations and hypercoordinated carbonium ions in liquid media. Magic acid and other superacids are also used to catalyze isomerization of saturated hydrocarbons, and have been shown to protonate even weak bases, including methane, xenon, halogens, and molecular hydrogen.