A glucose-containing mineral medium supplemented with 0.01% yeast extract is described upon which all the species of thermophilic and thermotolerant fungi tested will grow. Thirteen of the 21 species do not require the yeast extract supplement for growth.Using this solid, supplemented mineral medium, the pH and termperature optima for growth of all strains were measured. No correlation was found between temperature optimum and pH optimum among members of the group tested.