Thorough hand disinfection in hospitals is essential to prevent nosocomial infections. Health care workers are trained and instructed on when and how to use hand sanitizers during apprenticeship training and continuing education, but up to now there is no automatic system to give immediate feedback about the quality of a hand disinfection in daily clinical routine. We propose a method that is capable to evaluate the quality of a hand disinfection using thermal imaging. It is the first part of a medical cyber-physical system that monitors compliance and quality of hand disinfection. Our setup consists of a thermographic camera mounted in a black box. Image sets of the hands are taken before and after disinfection, so that the resulting temperature difference gives an objective measure about the quality of the disinfection. The main advantage of our system is its suitability for everyday use and its feasibility to be embedded into existing medical networks.