A coated cutting tool is composed of one or more layers of refractory compounds of which at least one layer is single-phase α-alumina with a pronounced columnar grain-structure and strong texture in the [300]-direction. The alumina layer is preferably deposited by CVD (Chemical Vapor Deposition) and the preferred microstructure and texture are achieved by adding a second metal halide, and a texture modifying agent, to the reaction gas. When coated cemented carbide cutting tools according to the invention are used in the machining of steel or cast iron, several important improvements compared to prior art have been observed, particularly in the machining of nodular cast iron.