Abstract: Device to prevent the formation of condensate in compressed gas coming from an oil-injected compressor element (2) which is connected to an oil separator (9) which is connected to the above-mentioned compressor element (2) by means of an injection pipe (12), and whereby a cooler (14) is provided in the above-mentioned injection pipe (12) which can be bridged by means of a bypass (21), characterised in that it is provided with a controlled mixing valve (16) which is connected to the above-mentioned injection pipe (12) and to the above-mentioned bypass (21), and with a control device (38) for controlling said mixing valve (16) for the adjustment of the compressed air temperature (Tw) by adjusting the flow distribution through the mixing valve (16).