The hydride ion transfer reaction leading to CH3+ in collisions of CD3+ and CH4 was investigated in beam scattering experiments in the collision energy range 1-3 eV (center-of-mass). The reaction proceeds through the formation of an intermediate complex; the angular scattering data are consistent with a structure of the critical configuration of the intermediate being (D3C-H-CH3)(+) with R(C-H-C) approximate to 2.5 Angstrom. The formation of CD2H+, which is viewed as a backward decomposition of the complex to the reactants accompanied by a partial H-D scrambling, involves an analogous critical configuration at T = 3 eV.