In mycelial acetone powder of the basidiomyceteOudemansiella mucida, the presence of enzymatic systems of NADH2-oxidase and-dehydrogenase type and of NAD+-dependent alcoholdehydrogenase (using ethanol as substrate) has been detected. NADH2-oxidase has its optimal pH value in the region of 6,0 and is not too active. NADH2-dehydrogenase which reduces 2,6-dichlorophenolindophenol is very active, may be eluted from the mycelial preparation with water and its adequate pH is in the region of 6,2. On the other hand, NADH2-dehydrogenase reducing triphenyltetrazolium chloride is non-eluable with water, its activity depends on the presence of menadione and its adequate pH lies in the region of 7,4.