A method is described for the determination of acid volatile sulphide in sediments. Sulphide is released using 5.93 M hydrochloric acid and the resultant solution is separated from the sediment by filtration in a sealed system of syringes. The concentration in solution is determined spectrophotometrically as ethylene blue. The procedure, which has been used successfully for several years, uses simple equipment and is more rapid than the alternative distillation method. The limit of detection is 0.3 µmol 1–1 in solution, 2 µg g–1 expressed as mass of sulphide in dry mass of sediment. The relative standard deviation for standards was 1–3% in the concentration range of 15–28 µmol 1–1 and 2–7% in the range 4–15 µmol 1–1. For a sediment sample containing 118 µg g–1 it was 5%.