Spin-orbit density functional theory method implemented in the NWCHEM program package has been employed with the shape-consistent relativistic effective core potentials to calculate spectroscopic constants (bond lengths, frequencies, and dissociation energies) and estimate spin-orbit effects for 6th(Tl-At)- and 7th(113-117)-row element monohydrides. Results calculated with local density approximation and gradient-corrected approximation of the exchange-correlation functional are usually similar to those of other all-electron relativistic density functional approaches. The spin-orbit effects on the spectroscopic constants are in good agreement with previous two-component coupled-cluster singles and doubles with perturbative triples results calculated with same relativistic effective core potentials and basis sets. Spin-orbit density functional theory calculations with extended basis sets and extensive set of functionals for TlH, (113)H, PbH, (114)H, and PbO molecules indicate that there could be substantial variations among functionals and that the hybrid functionals produce the results in excellent overall agreement with empirical measures. (C) 2003 American Institute of Physics.