All-inorganic caesium lead-halide perovskite $$\hbox {CsPbBr}_{3}$$ CsPbBr3 and $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 powders have emerged as attractive optoelectronic materials owing to their stabilities and highly efficient photoluminescence (PL). Herein we report a facile chemical route to prepare highly luminescent monoclinic $$\hbox {CsPbBr}_{3}$$ CsPbBr3 and tetragonal $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 powders at room temperature. The $$\hbox {CsPbBr}_{3}$$ CsPbBr3 powders exhibit regular crystal shape and demonstrate polyhedral geometry with an average particle size of 10 $$\upmu $$ μ m. The $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 powders show platelet morphologies and the lateral sizes of the particles are from 5 up to 200 $$\upmu $$ μ m. Both $$\hbox {CsPbBr}_{3}$$ CsPbBr3 and $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 powders present a narrow emission line-width and PL emission of 528 and 527 nm, respectively. A direct band gap of 2.35 eV and an indirect band gap of 3.01 eV are calculated for $$\hbox {CsPbBr}_{3}$$ CsPbBr3 and $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 powders, respectively. In addition, the monoclinic $$\hbox {CsPbBr}_{3}$$ CsPbBr3 can be transformed to tetragonal $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 in the presence of water. The large-scale synthesis of $$\hbox {CsPbBr}_{3}$$ CsPbBr3 and $$\hbox {CsPb}_{2}\hbox {Br}_{5}$$ CsPb2Br5 will be advantageous in future applications of optoelectronic devices.