Atomic hydrogen1H0has four spin states. It is not well known that the upper two, in its electronic ground state, cross at a sufficiently high externally applied magnetic field Bx(ca. 17 T). The magnetic resonance spectra show particular effects in the crossing region. In the present work, we predict the relevant field-swept spectra at selected fixed frequencies, for1H0encapsulated in crystalline alpha-quartz powder, using the known spin Hamiltonian parameters derived from single-crystal EPR measurements. It was found that there is a 5 GHz frequency region in which spectral effects from the crossing can be observed.