We consider the spin-exchange in ultracold collisions of hydrogen (H) and antihydrogen (H) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange inH − H collisions is basically driven by the strong force between proton and antiproton, that spin-exchange cross-sections are proportional to the difference of singlet and triplet strong force S-wave scattering lengths, while the strong force effects are enhanced about 10 9 times due to long range atomic forces. We show that any difference in hyperfine structure of H andH ( CPT violation ) manifests itself in radical change of spin-exchange cross-sections energy behavior.