W2S8Ag4(AsPh(3))(4) was prepared by gently heating the solid-state reaction mixture of (NH4)(2)WS4, AgBr, and AsPh(3). Its structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the triclinic space group P ($) over bar 1 (No. 2), with a = 12.440(2) Angstrom, b = 13.793(5) Angstrom, c = 11.513(3) Angstrom, alpha = 96.41(2)degrees, beta = 108.10(2)degrees, gamma = 93.52(2)degrees, V = 1853.3(9) Angstrom(3), and Z = 2; R = 0.041, R(w) = 0.060. The structure can be described as a hexagonal prism shaped cage that consists of two identical butterfly shaped WS4(AgAsPh(3))(2) segments. These segments are interconnected by four relatively long Ag-S bonds. The electronic spectrum, cyclic voltammogram, and X-ray photoelectron spectrum of the cluster were obtained. Nonlinear optical (NLO) properties of the cluster were studied with a 7-ns pulsed laser at 532 nm. The cluster exhibits both optical self-focusing and optical nonlinear absorption (n(2)(eff) = 5.9 x 10(-17) m(2) W-1; alpha(2)(eff) = 2.8 x 10(-9) m W-1; examined in a 1.3 x 10(-4) mol dm(-3) acetonitrile solution). The corresponding effective third-order NLO susceptibility (chi(eff)(3)) of the cluster is 1.7 x 10(-10) esu. These nonlinear optical properties of the cluster are compared with those of butterfly shaped clusters and those of other known NLO materials.