Acid catalysis is a common strategy in synthetic organic chemistry and biochemistry to increase the susceptibility of a target molecule to nucleophilic attack.

Acid catalyzed reactions include hydration of alkenes, dehydration of alcohols, cleavage of ethers, (and epoxide ring opening), nucleophilic additions to aldehydes and ketones, and the category of acyl transfer reactions.

Acid catalysis is an essential step in the catalytic mechanisms of many enzymes. For example, the active site of lysozyme, an enzyme devoted to immune protection, contains a particular glutamic acid residue that donates a proton to the ether linkage in the polysaccharide component of a bacterial cell wall facilitating lysozyme's ability to cleave the polysaccharide.