A superconducting transition around 15-16 K is reported for metastable, as-melted ScNi2B2C samples. Zero resistivity T(c)(zero) was observed at 14.6 K with T(c)(onset) around 16.5 K. A consistent diamagnetic T(c) signal was observed around 14.8-15.6 K. The new superconducting phase was identified as isostructural to the quaternary LuNi2B2C-type phase with tetragonal lattice parameters a = 3.34 angstrom and c = 10.2 angstrom. This superconducting phase is unstable due to the extremely small Sc3+ ionic size, where the Sc atom is located in the cavity formed by the B-Ni-B-C network and no superconducting transition could be observed down to 5 K after 1050-degrees-C annealing.