Hand hygiene is critical for infection control, but studies report poor transfer from training to practice. Hand hygiene training in hospitals typically involves one classroom session per year, but psychomotor skills require repetition and feedback for retention. We describe the design and independent evaluation of a mobile interactive augmented reality training tool for the World Health Organisation (WHO) hand hygiene technique. The design was based on a detailed analysis of the underlying educational theory relating to psychomotor skills learning. During the evaluation forty-seven subjects used AR hand hygiene training over 4 weeks. Hand hygiene proficiency was assessed at weekly intervals, both electronically and via human inspection. Thirty eight participants (81%) reached proficiency after 24.3 (SD=17.8) two-minute practice sessions. The study demonstrated that interactive mobile applications could empower learners to develop hand hygiene skills independently. Healthcare organizations could improve hand hygiene quality by using self-directed skills-based training combined with regular ward-based assessments.