Naphthalenesulfonates are derivatives of sulfonic acid that contain a naphthalene functional unit. A subfamily of compounds are the aminonaphthalenesulfonic acids, which describes precursors to several azo dyes.

The alkylnaphthalene sulfonates are used as superplasticizers in concrete. They are produced on a large scale by condensation of naphthalenesulfonate or alkylnaphthalenesulfonates with formaldehyde. Also called water reducers, they improves the flowability of concrete (before it sets), which allows for high-strength, high-performance concrete and mortar with lower water-to-cement ratios.