We have carried out relativistic complete active space multi-configuration interaction followed by multi-reference configuration interaction computations including spin-orbit effects for the electronic states of the superheavy element 113 and (113)H. It is demonstrated that (113)H exhibits unusually short bond length and large dissociation energy due to large relativistic effects including spin-orbit effects. The 6d-spin-orbit-correlation effects are shown to be very important for (113)H. (C) 2002 Elsevier Science B.V. All rights reserved.