The solution-phase absolute rate constants (23 °C) for the abstraction by atomic hydrogen of 1°, 2°, and 3° allylic hydrogens have been calculated by determining the relative rates of abstraction vs addition, since the absolute rate constants for addition is known. The absolute rate constant for benzylic abstraction by deuterium has also been determined. The rate ratios for 1°, 2°, and 3° allylic abstraction are remarkably similar to those reported for the ratio of rate constants for methyl radical abstraction. The determinations of the rate constants were based on the values for the relative rates of abstraction/addition using atomic deuterium, / , the absolute rate constant for the addition of hydrogen to an olefin, , and the deuterium isotope effects for both addition, / , and abstraction, / .