We have studied the potential energy surface for the reactions of BH2+ with H-2, methane, ethylene and acetylene at the CCSD(T)/cc-pVTZ//MP2(full)/cc-pVTZ level and the reaction of BH2+ with ethane at the CCSD(T)/ 6-311 G(d,p)//MP2(full)/6-311G(d,p) level of theory. A complete survey of the potential energy surfaces is presented and the structures of the stationary points and the mechanisms of these reactions are discussed. The calculations suggest that the products of these reactions are formed by addition and elimination of a hydrogen molecule, effectively activating the carbon-hydrogen bond. Furthermore, theory also suggests that elimination of HD is the sole product in the reaction of BD2+ With ethane; however, H/D scrambling occurs to some extent in the reaction with acetylene whereas it is complete in the reaction with ethylene. Therefore, loss of H-2, HD, and D-2 is predicted, in agreement with experiments. In addition, elimination of CH4 can also be produced in the reaction of BH2+ with ethane, even with BD2+ as reactant. Although the products of the carbon-carbon bond activation are also exothermic in the reactions of acetylene and ethylene, they are prevented kinetically. The remarkable electrophilic properties of BH2+ are presented and discussed as well as details on the bonding structure of the three-center two-electron bonds characteristic of these compounds.