Extracellular α‐amylases I and II, produced by a facultative thermophile Bacillus thermoamyloliquefaciens KP 1071 capable of growing at 30–66°C, were purified to homogeneity. α‐Amylase I consisted of a single polypeptide with methionine residue at the NH2‐terminus. α‐Amylase II consisted of two equivalent polypeptides each comprising a methionine at the NH2‐terminus. α‐Amylase I hydrolyzed endotypically α‐1,4‐bonds in glycogen, amylopectin and β‐limit dextrin, but not their α‐1,6‐bonds. α‐Amylase II degraded amylopectin and β‐limit dextrin in exo‐fashion by cleaving preferentially α‐maltose units from the non‐reducing ends and hydrolyzing their α‐1,6‐branch points. α‐Amylase II hydrolyzed maltotriose, phenyl‐α‐maltoside, α‐ and β‐cyclodextrins and pullulan, whereas α‐amylase I had no activity for all these sugars. α‐Amylases I and II hydrolyzed maltotetraose, maltopentaose, α‐limit dextrin and amylose, but they were inactive for maltose, isomaltose and panose. It was suggested that α‐amylase I is the most thermostable type of hitherto known maltotriogenic endo‐acting α‐amylases, and α‐amylase II is the first maltogenic exo‐acting α‐amylase able to split α‐1,6‐bonds in amylopectin.