We extend volume‐integral eddy‐current models that have been developed for conventional nondestructive evaluation (NDE) to tissue characterization and hyperthermia thermometry. Hyperthermia is a method of cancer treatment in which the tumor is selectively heated electromagnetically relative to the surrounding tissue. The problem is to noninvasively measure the temperature of the tumor, so that the treatment can be properly handled. In past research we have reported on inverse methods in eddy‐current NDE, and we demonstrate how these inversion algorithms can be applied to solve this problem. © 2003 American Institute of Physics