The structure resulting from the solidification following pulsed-laser-induced melting of a thin NiSi layer on a substrate of (111) silicon has been investigated by Rutherford backscattering spectrometry and transmission electron microscopy. The occurrence of a novel metastable phase epitaxial with the substrate is shown. In a restricted energy density range the competi-tion between the nucleation of orthorhombic NiSi and the epitaxy of the metastable phase gives rise to a bilayer structure. The critical solidification velocity at which the nucleation of the orthorhombic phase is suppressed has been estimated.