In this study,litter and upper surface of soil were collected from a mixed deciduous forest in Kanchanaburi, Thailand. Different amounts of urea (5, 10, 15, 20, and 40 mg N per gram dry soil) were applied separately to mixtures of the litter in plant pots. Only Coprinopsis spp. occurredon the urea-treated soils. Morphological and physiological characteristics of the Coprinopsisspecimens were examined. All isolates obtained from the soils were C. cinerea. Litter decomposing abilities of C. cinerea and other Coprinopsisspp. in ammonia fungi wereexamined. All tested Coprinopsis spp. had strong decomposing activities of CM cellulase and xylanase. Coprinopsis spp. except for C. cinerea and C.neolagopus also showed relatively strong ligninolytic activity. Some isolates of C. cinerea from different biogeographicalareas including Thailand showed positive reactions of ligninolytic activities except for RBBR and p-cresol tests suggesting C. cinerea would simply have tyrosinase activity. It may be concluded that Coprinopsis spp. would be one of key species of ammonia fungi which contribute to the decomposition of plant materials under nitrogen-enriched environmental though decomposition abilities of those species showed high variation among isolates.