Abstract: Novel hyperactive Hermes Transposase mutants and genes encoding them are disclosed. These transposases are easily purified in large quantity after expression in bacteria. The modified Hermes Transposases are soluble and stable and exist as smaller active complexes compared to the native enzyme. The consensus target DNA recognition sequence is the same as the native enzyme and shows minimal insertional sequence bias. These properties are useful in whole genome sequencing applications that involve sample DNA preparation requiring simultaneous fragmentation and attachment of custom sequences to the ends of the fragments. Methods and compositions using these transposases in fragmentation and 5? end-tagging are also disclosed.