Abstract: This Paper reports on the coordination compound grown in a gel reaction of 18-crown-6 with cobalt(Ⅱ) chloride and barium thiocyanates. The crystal contains water molecules with the chemical formula of [Ba(C₁₂H₂₄O₆)(H₂O)₂]·[Co(NCS)₄]. Its composition was determined by elemental analysis and X-ray spectrum. Adark blue crystal of dimensions 0.2-0.7 mm was selected.The intensity data were collected on a Enraf-Noius CAD-4 four-circle diff-ractometer by using MoK_α radialion(=0.71069A). There were 5553 independent reflections and 4254 visible intensity data were obtained. The structure was solved by Patterson method and Fourier method and refined by block-least square method,R= 0.029, R_w= 0.031. The crystal belongs to the rhomb system and the space group is D_2h¹⁶-P_nma with crystal parameters α=12.136(3)Å, b=14.586 (3)Å, c=16.475(4)Å, α= β=γ= 90, V= 2916.19ųand Z=4. The calculated density of the crystal is D_c= 1.619g/cm³and the linear absorption coefficient is = 22.2cm^-1(MoK_α).