The maximal enzymatic activity of crude amylase produced in the batch culture of Clostridium beijerinckii strain AM21B grown in PY medium with starch was obtained at 55-degrees-C and in an acidic pH range of 4.6 to 5.4. Amylase was produced in the culture medium after 4 h (46.6 units) and reached a peak (405.5 units) after 12 h cultivation at 36-degrees-C, pH 6.0. Although the most efficient production of amylase, hydrogen and cells was achieved at 36-degrees-C and pH 6.0, the maximal hydrogen evolution rate was found at 41-degrees-C and pH 7.0.