Order-disorder transition temperature (T-d) of the system (Ba1-xSrx)(2)In2O5 and Ba-2(In1-xGax)(2)O-5 was investigated by means of electrical conductivity measurements and dilatometry. It was found that the substitution of Sr2+ for Ba2+ increased the T-d, and the substitution of Ga3+ for In3+ decreased the T-d, at which the increasing rate of the electrical conductivity decreased. A tolerance factor, which has been used for the perovskite-type structure, was applied for the present brownmillerite systems, in order to understand the T-d shift. As the tolerance factor approached 1, the T-d decreased linearly.