We demonstrate the synthesis of cuboid MAPbBr(3) (MA = CH3NH3) microcrystals and subsequent conversion into open-box-like MAPb(Br1-xIx)(3) (0 <= x <= 1) microcrystals by anion exchange in MAI solution. During the substitution of Br- with I-, the initial cuboid framework of MAPbBr(3) crystals is retained. The preferential internal dissolution of MAPbBr(3) due to the surface coverage and protection of MAPb (Br1-xIx)(3) induces voids inside the cuboid crystals, finally leading to open-box-like iodide-rich MAPb (Br1-xIx)(3). By controlling the degree of anion exchange, the intense light absorption of the product is able to be tuned in specific wavelengths throughout the visible range. This solution-phase anion exchange approach provides a synthetic strategy in designing sophisticated organolead halide perovskites structures as well as tuning the band gaps for further applications across a range of possible domains. (C) 2015 Elsevier Inc. All rights reserved.