Polynapthalene sulphonate (PNS) is a cost effective dispersant and for this reason it is probably the most widely used dispersant. However, its use in some areas is limited for environmental reasons: it does not biodegrade in seawater and is toxic to algae.

The product is commercially available as both a liquid and a solid. The molecular weight of is from 6 to 15 kg/mol corresponding to the number of repeat units (n) from 20-50. However, there may be some fractions present with up to 300 repeat units.

These high molecular weight components may provide some dispersion through steric effects.

PNS dispersants can be used at temperatures up to 204°C (400°F).