[en] Hot hydrogen atoms with initial energies from 1.1 - 3.6 eV have been generated photochemically and used to study hydrogen abstraction reactions from alkanes. The integral reaction probability for H* + n-C₄D₁₀ was measured and a previous erroneous mesurement of IRP was corrected and explained. The isotope effect for abstraction of H versus D from various isotopically substituted ethanes was measured by a competitive technique both inter- and intra-molecularly. Additionally, the photolysis of methyl iodide at 185.0 nm was studied and new primary processes involving both the molecular elimination of hydrogen and the production of hot hydrogen atoms were tentatively identified