Hydrogen atom-induced deuterium adatom abstraction has been studied on the Si(100) surface from a desorption point of view. Abstraction of HD as well as collision-induced D-2 desorption are observed on the D/Si(100) surface during H beam exposure at 573 K. For 1 ML D-ad precoverage, about 30% of the desorbed D atoms are ejected as collision-induced D-2 desorption at the very beginning of H(g) exposure. It is found that the decay of the HD and D-2 rates are affected by the total coverage, theta(H+D). The decay rate of the HD rate is much lower in the low coverage regime than in the high coverage regime. The nominal cross section of the former is 2.3 +/- 1.0 Angstrom(2), while for the latter 7.2 +/- 0.5 Angstrom(2). The HD rate curves show that the abstraction obeys nearly first-order kinetics towards D coverage, theta(D). On the other hand, the D-2 rate curves show that the collision-induced desorption obeys nearly fourth-order kinetics towards theta(D). Such HD abstraction is also observed on an oxygen-deposited D/Si(100) surface where the oxygen atoms are known to be incorporated between Si atoms. The observed decay rate of the HD rate is extremely low, with a cross section of 1.5 +/- 1.0 Angstrom(2). The reaction kinetics are well understood by adopting the kinetics model recently proposed by Flowers [Surf. Sci. 396, 227 (1998)]. The abstraction of HD may be due to an Eley-Rideal mechanism rather than to a hot atom mechanism. Collision-induced D-2 desorption may take place upon encounter of two dideuteride species via an isomerization reaction at quasiequilibrium.