Soluble cyanide can be determined ins oil samples by differential pulse polarography. Interference from sulphide is avoided by treating the alkali-stabilized sample solutions with lead carbonate prior to distillation of cyanide from the soil extract. Less than 10 μg l-1 cyanide can be determined accurately, depending on teh weight of sample taken and the final collection volume. For a 100-g soil sample, the detection limit is 5 ng g-1, which is similar to the limit of a standard spectrophotometric method. Relative standard deviations are 1-3%.