Fourier-transform microwave spectroscopy was applied to observe the J = 1-0 rotational transition of the H-2-HCN complex for both the ortho-and para-H-2 species to obtain improved molecular constants by an analysis combined with the millimeter-wave data. It was confirmed that the para-and ortho-H-2 species have different configurations: namely H-2 is attached to the H end of HCN in the former, while to the N end in the latter. For the ortho-H-2 species, the hyperfine splitting due to the magnetic interaction between the hydrogen nuclei was observed to give the nuclear spin-spin coupling constant d(H) = 54.6(38) kHz. (C) 2012 Elsevier B.V. All rights reserved.