The viscosities and densities of rubidium bromide were determined in dimethyl sulfoxide (DMSO) + H(2)O mixtures of different compositions as a function of concentration [(0.01 to 0.06) mol.L(-1)] and temperatures [(25 to 45) degrees C] to obtain the Jones-Dole B-coefficient. The positive values indicated that the salt behaved as a structure maker in DMSO, and in DMSO + H(2)O mixtures, the B-coefficient values were less positive, showing a weak structure-making effect. On the other hand in H(2)O, B-coefficient values of RbBr were negative, showing the structure-breaking ability.