Chimeric alpha-amylases having the characteristics of high thermostability and good performance in starch degradation, especially high-temperature liquefaction processes, are provided. The alpha-amylases are chimeras of AmyL and AmyS enzymes, and are useful in starch degradation processes. Methods of making the chimeric enzymes, and methods of using the chimeric alpha-amylases for liquefaction, cleaning starch residue from a surface, and treating woven material to remove coatings. Kits for practicing the methods are provided. Polynucleotides encoding the chimeric amylases, vectors, and expression hosts also are provided.