Formation of C-(HH)-H-. . .-B dihydrogen bonded borane-trimethylamine dimer was investigated using ab initio and DFT-B3LYP methods using several basis sets. The (HH)-H-. . . contact distance of less than 2.4 angstrom was used as a criterion to infer the formation of dihydrogen bonds. MP2 was the only method, which consistently predicted the formation of the C-(HH)-H-. . .-B dihydrogen bonded dimer, with the stabilization energy in around 20 kj mol(-1). Further, molecular electrostatic potential derived charges as well as charges from the natural population analysis and AIM analysis support the formation of the dihydrogen bonding between oppositely charged hydrogen atoms. (c) 2005 Elsevier B.V. All rights reserved.