We report on electrically-active defects located between 0.054 and 0.69 eV below the conduction band edge in rutile single crystals subjected to reducing and hydrogenating heat treatments. Deep-level transient spectroscopy measurements recorded on samples subjected to different heat treatments are compared. In samples annealed in gas, three defect levels are commonly observed. One of these levels, , located 0.43 eV below the conduction band edge is tentatively assigned to a hydrogen-impurity complex. Two levels at 0.054 and 0.087 eV below the conduction band edge, which were present after all different heat treatments, are tentatively assigned as being related to O vacancies or Ti self-interstitials. Deep-level transient spectroscopy spectra of samples heat-treated in display a larger number of defect levels and larger concentrations compared to samples heat-treated in gas. treatments are performed at considerably higher temperatures. Four energy levels located between 0.28 and 0.69 eV, induced by annealing in , are tentatively attributed to O vacancy- or Ti interstitial-related complexes with impurities. [ABSTRACT FROM AUTHOR]