We synthesized polycrystalline samples of Ba{sub}(1-x)Sr{sub}xIrO{sub}3 (0 ≤ x ≤ 0.2) using a solid-state reaction method, and measured their magnetization, resistivity and thermopower. The thermopower of BaIrO{sub}3 slightly increases with decreasing temperature above T{sub}C, and is suddenly enhanced below T{sub}C = 180 K due to the pseudogap in the density of states. At 75 K, it reaches a maximum value of 230μV/K. With increasing Sr concentration, the thermopower systematically decreases, accompanied by a slight decrease of T{sub}C. For x = 0.2, the maximum value of the thermopower and T{sub}C are 50μV/K and 173 K, respectively. These results indicate that the gap is suppressed by chemical pressure due to the substitution of Sr for Ba.
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