Abstract: A rotary internal-combustion engine, comprising at least one fixed hollow body, and a movable body rotatable coaxially inside the fixed body, a chamber for a working fluid formed between the cylindrical bodies, at least one intake and at least one exhaust, at least one vane element associated with the outer surface of the movable body and extended in axial direction, at least one first and second partitions for dividing the chamber, the vane element, cooperating respectively with the intake to aspirate working fluid into the chamber, with the second partition to compress it, with the first partition to form a combustion chamber, and with the exhaust for working fluid expelling.