Optical admittance spectroscopy (OAS), supported by electron paramagnetic resonance (EPR) measurements, is used to identify the controversial vanadium acceptor levels in vanadium-doped semi-insulating (SI) 4H-SiC and 6H-SiC. The V 3+/4+ levels for the cubic site are likely located at E c - 0.67 ± 0.02 eV and E c - 0.70 ± 0.02 eV in 6H-SiC and E c - 0.75 ± 0.02 eV in 4H-SiC. A peak at 0.87 ± 0.02 eV in the 6H-SiC is tentatively assigned to the same transition at the hexagonal site and the associated transition in 4H-SiC is thought to occur near 0.94 eV. All assignments are supported by the observation of V 3+ in the EPR spectrum. © Springer-Verlag 2007.