A rotor for a thermal turbomachine, in particular a gas turbine, designed to conduct a medium, such as compressor air, in the interior of the rotor. In order to conduct the medium in the interior with low flow losses and at the same time to specify a rotor that can be produced comparatively simply and economically, a separately produced blade wheel is arranged between the mutually adjacent hub regions of the two rotor disks, and a sleeve is provided for fastening the blade wheel to one of the two rotor disks, which sleeve extends through the central opening of the one rotor disk and includes a collar serving as a stop at a first end of the sleeve and includes a second end opposite the first end, on which second end the blade wheel is fastened.