In situ C-13 and H-1 MAS NMR study of hydride transfer between C-13 and H-2 isotopically labeled isobutanes on acidic zeolites enabled to estimate the activation energy of this process for the first time and allow full re-evaluation of C-H bond activation mechanism at moderate temperatures. The hydride transfer was shown to occur on the methine position of the molecule. The rates of the intermolecular H/D exchange were measured at different temperatures, and the activation energy was determined to be ca. 55 kJ/mol. These new results definitively support the carbenium mechanism for alkane activation over zeolites through a bimolecular process. (C) 2013 Elsevier Inc. All rights reserved.