Cube shaped CaSn(OH)₆ particles were prepared at room temperature in aqueous medium. The samples showed blue light emission upon UV excitation. Luminescence studies have confirmed that blue emission from the sample is arising due to self trapped exciton-hole recombination. XRD and luminescence studies have revealed that lanthanide ions such as Eu³⁺ get incorporated in the lattice of CaSn(OH)₆ cubes and occupy Ca²⁺ site in the lattice.