Abstract Spills of hazardous chemicals which are water soluble are more difficult to treat than other spills where the chemical forms a separate phase. There is a need to develop treatment techniques which are applicable to a range of chemicals, which reduce the adverse environmental effects of the spill and do not introduce any additional environmental problems. Four techniques are examined in this paper: neutralization is effective for acids and bases, solvent extraction is effective for some organic chemicals, and precipitation and chelation are effective against some toxic metals. Each technique has some important practical limitations if further adverse environmental effects from the treatment agent are to be avoided. However, for each technique, one or more reagents can be selected which are effective, non-toxic and readily available.