Acid sulfate soils, which are very xoidespread in the coastal plains of the west coast of Peninsular Malaysia, are characterized by low pH and high extractable AL A study was carried out to characterize and classify acid sulfate soils in Pulau Lumut, Selangor, Malaysia. The study showed that these soils were morphologically variable in nature. Yellowish jarosite mottles were a common feature in the oxidized layer of the soils. The clay fraction of the soils was dominated by kaolinite, smectite and mica, with minor amounts of mica-mixed layers, jarosite, halloysite andgibbsite. Depending on the depth of the jarosite layer, the soils can be classified as Sulfic Tropaquepts or Typic Sulfaquepts .