Reactions of Fe+ with DzO and FeO+ with Dz are studied as a function of translational energy in a guided-ion beam tandem mass spectrometer. In the former system, the only products observed from single-collision events are FeD+ and FeOD+. These products are formed in endothermic reactions. At low energies, the FeODZ+ adduct is also observed, a result of secondary stabilizing collisions with D2O. Results for Fe+ produced in two different sources are analyzed to yield state-specific cross sections for reaction of the a6D ground and a4F first excited states of Fe+. In the reaction of FeO+ with D2, three ionic products (Fe+, FeD+, and FeOD+) are observed. An inefficient exothermic process that forms Fe+ + DzO is observed, consistent with known thermochemistry; however, formation of Fe+ + DzO also occurs via another more efficient pathway that involves a reaction barrier of -0.6 eV. The FeOD+ channel also proceeds via a pathway involving a reaction barrier of the same energy. Results for both the Fe+ + DzO and FeO+ + Dz systems are used to derive potential energy surfaces for these systems.