Acicular nickelous ethyl xanthate, Ni (EtX)_2, crystals often grow from the acetone solution with usual platy square crystals. The crystal structure of orthorhombic form corresponding to the platy square crystal has been determined by Franzini (1963). The acicular one found in the present work is determined to be triclinic by the x-ray method. The crystal structure has been solved by the Patterson method and refined using the 4-circle x-ray diffraction data. Space group: P1, a=8.835, b=10.299, c=8.143 A, α=91.81°, β=122.33°, γ=70.52°