The weak dihydrogen-bonded interactions are found between HB BH ( 1螖 g) and HM (M = Li, Na, K, BeH, MgH or CaH) using MP2 and CCSD(T) methods with 6-311++G(3df,2p) and aug-cc-pVTZ basis sets. The binding energies follow the order of HB BHHK > HB BHHNa > HB BHHLi ...