Control over reactive and non-reactive cross-sections in 3D atom–diatom scattering is shown to be possible using a superposition of non-degenerate ro-vibrational states of the target-diatomic molecule. Depending on the phase and magnitude of the coefficients which describe the initial superposition state, one can, through quantum interference, enhance or suppress the reactive or non-reactive scattering to predetermined product states. Fully converged 3D quantum computations reveal extensive control over the reactive/non-reactive branching ratios in the D+H 2 →DH+H and the H+H ′ D→HH ′ +D; HD+H ′ reactions, where H and H ′ denote hydrogen atoms which are considered distinguishable.