The yields of H atoms in the thermal decomposition of i-C4H10 -> products (1) and n-C4H10 -> products (2) are measured at 1470-1800 K behind reflected shock waves. A comparative method is used to evaluate the branching fractions for i-C4H10 -> CH3 + i-C3H7 (1a) and n-C4H10 -> 2C(2)H(5) (2b), where, C3H6 is used as a reference. The branching fractions for (1a) and (2b) are expressed by k(1a)/ k(1) = (0.64 +/- 0.14) (10 T-3/ K) - (0.06 +/- 0.23) and, k(2b)/ k(2) = (0.050 +/- 0.059)(10 T-3/ K) + (0.49 +/- 0.10), respectively. Contributions of the roaming channels are less than 12 and 5% for i-C4H10 -> CH4 + C3H6 (1b) and n-C4H10 -> CH4 + C3H6 (2c), respectively. (C) 2017 Elsevier B. V. All rights reserved.