Abstract: The original Bi-based oxyhalide is the Sillen family expressed by [M2O2][Xm] or [M3O4+n][Xm] (m=1-3, X=halide, M=Bi) where bismuth oxide-based fluorite-like layers, [M2O2] or [M3O4+n], are intergrown with single, double, and triple halide. The band gap of BiOX is strictly dependent on the halide participated in its composition and ranges from 3.19–3.44, 2.64–2.91 and 1.77–1.92 eV, respectively for Cl, Br and I. Bismuth nitrate pentahydrate and potassium bromide were applied to synthesize the product in a domestic microwave instrument. The SEM images showed the microflowers were comprised of nanosheets with the thickness of about 54 nm. From energy dispersive X-ray analysis, its empirical formula was estimated to be Bi1.75O13.66Br. Fourier transform infrared spectroscopy showed that the peaks at 565 and 815 cm-1 were attributed to the stretching vibration of Bi-O. with a band gap energy of 3.58 eV, it showed a high photocatalytic performance in photodegradation of Rhodamine B.