Abstract: A portable motor-driven compressor set on which the output shaft of a motor drives an opposed-piston compressor rigidly connected to the motor frame, characterized by the fact that the compressor consists of a pair of heads arranged one on top of the other and each having a valve plate, a cylinder for a respective piston, and a half casing, all formed in one piece and preferably die-cast in aluminium; the aforementioned half casings being secured together end-to-end with their respective cylinders coaxial, and the pistons also being formed integral in one piece and with a respective connecting rod having a slot housing the drive shaft, and a seat for a cam controlled by the aforementioned shaft.