The mechanisms of the doublet CH radical reaction with ammonia, water, and hydrogen peroxide were computationally studied with complete basis set ab initio methods. Several different reaction pathways are considered, including hydrogen transfer, fusing of radicals, and the CH radical insertion reaction. It was demonstrated that the insertion reaction has the lowest activation barrier. Enthalpies of several reactions were explored, and it was demonstrated that complete basis set ab initio method is highly accurate for computing thermal properties of these chemical systems.