Palynological study of northern Thailand coal and oil deposits indicates a similar palynological association to that of the Borneo region. Coal petrographic studies of these deposits show variations in the lipnite macerals, especially alginite types. The oldest of these coal and oil deposits, which are of Late Oligocene to Early Miocene age, are dominated by Botryococcus sp. or Botryococcus -related algae. Thick-walled lamaginites and spores and pollen of temperate affinity, are found in some areas. By contrast, thin-walled lamaginite is dominant in late Middle Miocene time. Resinite, suberinite, and cutinite are dominant in forest swamp coal deposits whereas alginite, cutinite and lycopodium spores are dominant in lacustrine environments. Exsudatinite is common even at early levels of maturation. These liptinite macerals can be major sources of oil and gas. ã 1999 Elsevier Science Ltd. All rights reserved.