By tilting the needle like crystals in a partially crystallized Ni P amorphous alloy in a transmission electron microscope, the lattice type of a metastable phase with approximate composition Ni2.2 P has been uniquely determined to be hexagonal, α = 6.73? and c = 9.42?. In the c direction, the layer stacking sequence is AA…. High resolution lattice image of the (001) planes as well as the diffraction streaks in c* direction both indicate the presence of one dimensional disorder in stacking of the hexagonal layers.