The Schiff base 2-ethoxysalicylaldehydethiosemicarbazone (HL) derived from 3-ethoxysalicylaldehyde and thiosemicarbazide, and its centrosymmetric trinuclear cadmium(II) complex [Cd3L4]center dot 2NO(3)center dot 2H(2)O, have been successfully prepared. The structure of the complex was characterized by elemental analyses, IR spectrum, and single-crystal X-ray crystallographic determination. The complex crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 15.102(2) angstrom, b = 19.049(2) angstrom, c = 21.303(3) angstrom, beta = 107.212(2)degrees, V = 5853.8(12) angstrom(3), Z = 4, R-1 = 0.0318, and wR(2) = 0.0765. The Schiff base coordinates to the Cd atoms through the phenolate O, ether O, imino N, and S atoms. The terminal Cd atoms of the complex are coordinated by six donor atoms from two Schiff base ligands. The central Cd atom of the complex is coordinated by eight O atoms from four Schiff base ligands. The effect of the Schiff base and the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.