A new open framework indium sulfide, In10S18[(H2O)4(C6H18N4H2)1.5(C6H18N4H3)] (SCU-1), has been synthesized under hydrothermal conditions. X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscope (SEM), thermogravimetric analysis (TGA) and elemental analysis were employed for the characterization of SCU-1. The resultant crystallizes in the tetragonal space group P41212 (No. 92) with a = b = 19.702(2) Å, c = 31.509(5) Å, V = 12,231(3) Å3, and Z = 8. The crystal framework has a large pore volume of more than 51%. The charge balance of the anionic framework [In10S18]6− is maintained by the template cations in the cavity spaces. The framework remained at higher crystallinity after about 90% of the extra-framework amines were removed by exchanging with K+. The as-synthesized material can undergo ion exchange with various metal cations in the selectivity series as Cu2+ > Cr3+ > Cs+ > Zn2+ > Co2+ > Sr2+ > Mn2+ with the total ion exchange capacity (IEC) of 0.59 mmol/g.