A cyclodextrin glucanotransferase (CGTase)-producing thermophilic bacterium (strain 2/2) was iso-lated from Bulgarian hyperthermal springs with a temperature of 102 °C and a pH value of 8.0—8.8. The strain was aerobic, Gram-positive, and endospore forming with a temperature optimum of about 60 °C and a pH optimum of about 9.0. According to morphological, cultural and biochemical characteristics, and molecular properties, the isolate was identified as an alkalotolerant member of the species Bacillus stearothermophilus. The effect of various carbon sources on CGTase production was studied and glucose (0.5%) was found to be the most suitable substrate for CGTase biosynthesis (10 U/ml). The addition of glutamic acid (0.1%) to the medium increased the CGTase yield 1.7-fold and the specific enzyme activity 1.5-fold.