The ground states of HMHe + (M=Li, Na, K) and HMHe 2+ (M=Be, Mg, Ca) have been investigated using relativistically-corrected CCSD(T) and IC-MRCI. The HLiHe + , HBeHe 2+ , HNaHe + and HMgHe 2+ ions were found to be linear in the ground state. Conversely, HKHe + and HCaHe 2+ were quasi-linear, with 2A′-2Σ+ barrier heights of ca. 2 and 5cm −1 , respectively. Structural and energetic trends are consistent with H and He sharing covalent and electrostatic bonds with the metal ion, respectively. These trends are also seen to be strictly dependent on the polarisability of the central metal ion.