[en] The tunneling corrections for the rate constants of hydrogen abstraction by hydrogen atoms below 77⁰K have been calculated for the reactions with methane, ethane, propane, and isobutane assuming gas phase activation energies and frequency factors. It has been shown that the use of the unsymmetrical Eckart potential function is effective in reproducing half-lives which are consistent with the experimental results that thermalized hydrogen atoms are not trapped even at 4.2⁰K in irradiated alkanes other than methane. Qualitative trends for the effects of the structural and isotopic difference on the tunneling abstraction rate constants have been discussed based on these calculations. The results indicate that thermal H and D atoms may not be easily trapped even at 4.2⁰K in protiated alkanes other than CH₄, while H and D atoms might be trapped in some deuterated alkanes other than CD₄. This was confirmed by detecting the ESR signal from trapped D atoms in C₂D₆ irradiated at 4.2⁰K