This paper presents experimental data for a free-piston Vuilleumier machine, which was designed as a refrigerator for CFC-free cooling and air conditioning. The basic features of the Vuilleumier cycle and the free-piston operation, which is known from free-piston Stirling engines, are discussed briefly. Additionally, the design of the prototype is described. From the variety of the experimental data, the influence of the mean pressure and the three cycle temperatures on the refrigerating capacity and the COP are selected for presentation and detailed discussion in this paper. The results are used to deduce some general operating characteristics of a free-piston Vuilleumier refrigerator, which reveal its potential for CFC-free cooling and air conditioning.