Dispersants are the most commonly used chemical treating agent. Chemical dispersants are designed to break up surface oil slicks, and disperse the oil as fine droplets into the water column so that natural mixing action will dilute the subsurface oil concentration. This action transfers the oil from the waters surface into the water column. There it is dispersed by currents and subjected to natural processes such as biodegradation that render the oil harmless. If this process is effective, the oil is prevented from moving into sensitive environments or stranding onshore. This will eliminate or reduce the damage to important coastal habitats, marine life, or coastal facilities.

The dispersion process does move the oil from the surface to the water column. This potentially exposes the water column and near shore shallow bottom-dwelling organisms to oil. These oil concentrations however, are extremely low and decrease quickly, thus limiting overall impact to sensitive environmental resources. Since the very small chemically dispersed oil droplets are not prone to re-coalescing, the treated oil is unlikely to form tar balls or patties. Modern dispersant formulations are a mixture of low toxicity solvents and surfactants designed for use in the marine environment to disperse oil with minimal toxic consequences.