The density of states (DOS) plays a key role to understand the electronic structure of materials, to predict their macroscopic physical properties and their response to various external conditions such as temperature and pressure, etc. In this work, the DOS for three different concentrations of rubidium in the KTl structure type were calculated to observe the effect of the substitution as shown in Figure . The calculated DOS for three different concentrations show a good agreement and there is no significant difference observed between them. This clarifies that the electronic structure of K1-xRbxTl (x>0) is similar to KTl and the identifiable difference is due to the size effect or different ionic radii of rubidium.