An ab initio computational study of the properties of four linear dihydrogen-bonded complexes formed between the recently discovered argon-containing compound HArF and the XBeH (X = H, F, Cl and Br) molecules was undertaken at the MP2(full)/6-31++G(d,p) level of theory. The calculated complexation energy at G2MP2 level show that stability of complexes decreases as (HBeHHArF)-H-... > (BrBeHHArF)-H-... > (ClBeHHArF)-H-... > (FBeHHArF)-H-.... Atom in molecule (AIM) analysis is used to discuss effect of substitution on the (HH)-H-... bond length. (C) 2004 Elsevier B.V. All rights reserved.