The microwave and millimeter-wave spectrum of HeH2+ is reported over the frequency range 6-170 GHz. The observation of hyperfine structure in the spectra of some transitions made a clear distinction between the ortho- and para-hydrogen in the molecular ion. The hyperfine structure and double resonance Zeeman studies have enabled estimates of the quantum numbers involved in the transitions to be made. The Zeeman pattern in a 21.8 GHz doublet has been analyzed using an effective spin Hamiltonian with a case (B) basis set. This suggests an assignment of DeltaN=+1, N=10<--N=11. A similar analysis, in an extended hyperfine basis set, for the 15.2 GHz transition suggests an assignment of either DeltaN=0, N=3, or N=4 as appropriate assumption from which to refine the potential.