The measurements of rotational spectra and metal-hydrogen bond lengths for molybdenum and tungsten hydride complexes were recently completed in our laboratory. The W-Hand Mo-H bond lengths were obtained from high resolution rotational spectra of C5M5(CO)(3)H, C5H5W(CO)(3)H, C5H5Mo(CO)(3)D, and C5H5W(CO)(3)D. Data for five molybdenum and four tungsten isotopomers were obtained for both the normal and deuterium-substituted species. The asymmetric-top rotational parameters A, B, C, Delta(J), and delta(J) were determined from the least-squares fits and these results indicate that the structures of these complexes are nearly rigid. The hydrogen bond lengths were determined for both complexes using Kraitchman analyses. The molybdenum-hydrogen bond length for the C5H5Mo(CO)(3)H complex is r(Mo-H)=1.80(1) Angstrom. The tungsten-hydrogen bond length for the C5H5W(CO)(3)H complex is r(W-H)=1.79(4) Angstrom. Density functional theory (DFT) calculations. of the structures were performed to obtain the optimized theoretical structures for C5H5Mo(CO)(3)H and C5H5W(CO)(3)H. Results obtained from the DFT calculations are in good agreement with the experimental parameters, and the Mo-H value is in good agreement with previously reported Mo-H bond lengths for similar complexes. (C) 2004 American Institute of Physics.