A reciprocating compressor. A hollow cylinder tube contains a piston assembly having two pistons connected by a piston rod. At each end of the cylinder tube is an outer chamber between an end plate and an outer end of the proximate piston. These two outer chambers and the outer ends of the pistons define a power cylinder at each end of the cylinder tube. In the mid-portion of the cylinder tube, a center divider is situated between the pistons and has an aperture that allows the piston rod to reciprocate through it. The two inner chambers formed thereby and the inner ends of the pistons define two compression cylinders in the mid-portion of the cylinder tube. The two compression chambers share a suction manifold and a discharge manifold, but have independently operating suction and discharge valves.