The invention relates to a method for operating a steam cycle process for using the heat of an internal combustion engine (2), comprising a conduction circuit (4) in which a working medium circulates. Said conduction circuit (4) comprises at least one pump (6, 13), at least one heat exchanger (8), an expansion machine (10), a feedwater tank (14) for storing the liquid working medium, and a condenser (12). Components of the conduction circuit (4) are frost-proofed by partially evacuating the liquid working medium. After the end of the circulation of the working medium, at least one of the pumps (6, 13) continues to operate in order to evacuate the working medium at least from the pump (6, 13) which continues to operate.