•Layered chalcogenide with CdI2 crystal structure prepared by hydrothermal route.•Exploration of the possibilities for radionuclides’ uptake using layered chalcogenide.•Proposing ‘topotactic ionic substitution’ as major uptake mechanism. Ensuring environmental protection in and around nuclear facilities is a matter of deep concern. Toward this, layered chalcogenide with CdI2 crystal structure has been prepared. Structural characterizations of layered chalcogenide suggest ‘topotactic ionic substitution’ as the dominant mechanism behind uptake of different cations within its lattice structure. An equilibration time of 45min and volume to mass ratio of 30:1 are found to absorb 233U, 239Pu, 106Ru, 85+89Sr, 137Cs and 241Am radionuclides to the maximum extents.