The pure rotational transitions in the 220-460 GHz spectral range of TiO (X3Deltar) and TiN(X2Sigma+) have been observed using a source-modulated submillimeter-wave spectrometer. In addition, the two lowest rotational transitions of TiO at 63 and 94 GHz have been observed using molecular beam pump/probe microwave optical double resonance (PPMODR) technique. An improved set of spectroscopic parameters for TiO(X3Delta) was generated by combining the new PPMODR and submillimeter-wave absorption measurements. Similarly, an improved set of spectroscopic parameters for TiN(X2Sigma+) was generated by combining the new submillimeter-wave absorption measurements with the previously recorded PPMODR measurements (D. A. Fletcher, C. T. Scurlock, K. Y. Jung, and T. C. Steimle, 1993, J. Chem. Phys. 99, 4288). The determined Lambda-type doubling parameter for the TiO(X3 Delta) is compared with the theoretical model. Copyright 1998 Academic Press.