The present invention relates to a working fluid for a steam-turbine cycle process, said fluid comprising a working medium, a lubricant and preferably an emulsifier. The working medium is a C1 to C4 alcohol and/or a C3 to C5 ketone, optionally mixed with water. The invention also relates to a device for a steam cycle process, which device contains the working fluid, and to the use of the working fluid in an organic Rankine cycle. The lubricant is a hydrocarbon and the emulsifier is a surface-active substance.