Ab initio and density functional theory (DFT) calculations have been performed to determine the heats of reaction for the process C 1 6 H . + 1 0 → C 1 0 H . + 2 that takes place in an ion trap mass spectrometer. Comparisons have been made with the experimental and derived data available for this process. The theoretical values at the DFT level verify the experimental heats of reaction within 0.4-0.8 eV. Furthermore, the structure of the product ion, C 1 0 H . + 2 , has been investigated. Several structures have been proposed, and the ab initio and DFT geometry optimizations and frequency calculations have been performed to determine the most stable species. At the level of theory and the approximations that were used in this work, the linear form of C 1 0 . + 2 is the most stable species of three different geometries considered.