Abstract: A device is described for cooling and silencing a compressor or vacuum pump which is directly connected to an electric driving motor. Both the compressor and the driving motor can be immersed, and are arranged in a totally sealed container encasing a cooling and sound-absorbing liquid to such a level that the compressor or vacuum pump and driving motor are totally immersed in the liquid. The whole of the outer surface of the container is coated with sound-absorbing material, and at least one heat exchanger is arranged outside the container and the sound-absorbing material, the heat exchanger being in communication with the inside of the container so that the cooling and sound-absorbing liquid flows through the heat exchanger under the influence of the thermal circulation generated in the liquid.