Two charge states are observed for Ru in doped PbTiO3crystals using electron paramagnetic resonance (EPR). The two paramagnetic charge states are +3 and +5. Thegtensors for the Ru3+and Ru5+defects were found to be near axial:g∥&bartil;1.155 andg⊥&bartil;2.188 for the Ru3+center andge∥&bartil;2.0045 andge⊥&bartil;3.959 for the Ru5+center. Analysis of the EPR spectra by crystal field theory indicates that the Ru3+ions are in tetragonally distorted (elongated) octahedral sites, strongly suggesting that they substitute for the central Ti4+ions in the perovskite lattice. Analysis of the Ru5+EPR spectra indicate that this defect is also in an octahedral site with a very large zero field splitting parameter. The results suggest that both Ru3+and Ru5+can substitute for Ti4+in the perovskite lattice with self‐compensation. Last, it is found that optical illumination of the crystals with band‐gap light at low temperatures decreases the density of both Ru centers. ©1995 American Institute of Physics.