The salt [K(18-crown-6)][Mn(H2O)(2)Cr(ox)(3)](.)0.5(18-crown-6) (1) has been prepared and structurally and magnetically characterized. It crystallizes in the P2(1)/c space group [a = 21.011(2) angstrom, b = 11.265(2) angstrom, c = 15.748(3) angstrom, beta = 105.952(6)degrees, V = 3584(1) angstrom(3), and Z = 4] and contains [Mn(H2O)(2)Cr(ox)(3)](infinity) chains connected through hydrogen bonding to form 2D anionic networks. The magnetic exchange is ferromagnetic [J = + 2.23(2) cm(-1)] in the chain and also in between chains, reaching bulk ferromagnetic ordering below 3.5 K.